How to choose the right storage bin size for your shop floor

Bin sizing is arithmetic, not taste. Work from the part, the consumption rate and the shelf, using real ALKON dimensions, then trial three sizes before you commit a whole plant to one.

Sizing starts with the part, not the catalogue

Most bin buying goes wrong at the very first step. Somebody opens a catalogue, points at a size that looks about right for a handful of screws, orders two hundred, and six months later half the bins on the line are holding four pieces each while the rest are overflowing onto the shelf with a cardboard carton parked underneath to catch the spill. With 476 products spread across nine ranges in the ALKON catalogue alone, the odds of guessing correctly are poor. Bin sizing is arithmetic. It uses numbers you already have — part dimensions, daily consumption, replenishment interval, shelf depth — and once you have worked through it twice it takes about twenty minutes for a whole part family.

The method, in order, is this: measure the part as it actually lies, convert that into pieces per litre, work out the holding quantity from consumption and the real replenishment cycle, derate the bin volume to a sensible fill line, shortlist two or three candidate sizes, check them against your shelf depth and vertical pitch, check hand access with the gloves your operators actually wear, trial the shortlist for four weeks, and only then write it into a standard. Every step below is worked through with real dimensions from ranges we stock, so you can copy the arithmetic straight onto your own part list rather than reading theory.

One warning before you start. The same part number will often justify different bin sizes at different points in the plant, and that is not an inconsistency to be stamped out. A brass terminal at a Pune wiring harness bench may sit in a small front-opening bin holding half a shift's demand, while the same terminal in the central store sits in a tote holding a month, and in the kitting area it sits in a shelf bin holding one week of kits. Size each point of use separately against its own replenishment cycle. Trying to force one bin size across stores, kitting and line-side is the commonest reason a bin standard collapses within a year.

Measure the part the way it actually lies in the bin

Take the vernier to the part by all means, but understand that part dimensions alone will not give you a bin size. Loose components do not pack like bricks. Circlips lock together, tension springs tangle into knots, wire forms interlock, sheet metal clips fall into each other and lie flat in one heap and stand on edge in the next. A hundred pieces of the same part will occupy noticeably different volumes on different days depending on how they were tipped in. So the physical dimensions of the part answer only one question — the minimum internal length the bin must have — and a completely different measurement answers the volume question.

For volume, use the pieces-per-litre method. Take a one-litre graduated jug from the canteen, or any container whose internal volume you can calculate, and pour in a counted quantity of the part. Level it the way an operator would, by a single shake and no more, then read off the level. Repeat three times and take the worst case, because the worst case is what the storekeeper will hit on the day the bin overflows. If a hundred pieces settle at 250 ml, you have four hundred pieces to the litre including air, and that single number now drives every bin decision for that part number for the next several years.

Record the longest dimension separately, because it sets a hard floor no volume calculation can override. A 120 mm stud will not lie flat in a Hippo 612/T, whose inside box is 80 x 90 x 43 mm, and will not lie flat in a Rhino ARTB-05 at 95 x 89 x 43 mm either. It just clears the 117 mm internal length of a Supra SB 1 only if it is genuinely under 117 mm, which means a 120 mm stud goes in diagonally, jams the front lip and gets bent. The same stud drops into a Panda Shelf Bin 301, internally 293 x 86 x 55 mm, with room to spare. Length first, then volume.

Longest dimension of the part, including any bent tail, lead or thread projection
Pieces per litre measured by fill, not calculated from part geometry
Mass of one hundred pieces, weighed, divided by a hundred
Whether the part tangles, nests or stands on edge when tipped in
Whether it is picked by hand, by scoop, or counted out

Turning consumption into a holding quantity

A bin holds a quantity, and that quantity comes from two numbers: how fast the part is consumed, and how long it takes for a refill to arrive. Bin quantity equals consumption rate multiplied by replenishment interval, plus a safety margin. The trap is the replenishment interval. Do not use the number in the standard operating procedure; use the number you observe. If the milk run is scheduled every two hours but in practice the trolley comes twice a shift because the store has one man and he is also issuing against job cards, your replenishment interval is four hours, and a bin sized on the two-hour figure will starve the line every single day.

Here is a worked case. A pump assembly cell in Coimbatore consumes nine hundred retaining clips a day across one eight-hour shift. The store round trip is honestly four hours, so each bin must cover four hours of demand, which is four hundred and fifty pieces, plus a twenty-five per cent buffer for the day the trolley is late — call it five hundred and sixty pieces. The pieces-per-litre measurement came out at eleven hundred pieces to the litre, so five hundred and sixty pieces need slightly over half a litre of genuinely usable space. Hold that number; the next section turns it into a bin size.

Then apply the cap from the other direction. There is such a thing as a bin that is too big. Line-side bins holding a month of a part that is subject to engineering change orders are a write-off waiting to happen, and a bin holding six weeks of a fast-moving fastener at the bench means somebody carried thirty kilos of steel up to a workstation for no reason. Set an upper limit in days of cover for each zone — a common pattern is under one shift line-side, under one week at the kitting bench, and bulk in the store — and if the calculated quantity breaches the cap, the answer is a smaller bin and a more frequent milk run, not a bigger box.

Fill line, dead space and why you never size to the brim

Internal volume is not usable volume. Front-opening bins have a cut-away front lip so that a hand can get in, and anything filled above that lip will migrate out onto the shelf as the bin is slid in and out. Bins that stack need clearance so the bin above seats properly on the rim rather than on the contents. Pickers dig with a cupped hand and displace material upwards. Between these three effects, the honest planning figure is seventy to seventy-five per cent of the internal volume. Size on that and your bins will look tidy; size on internal volume and every bin in the plant will look like it is about to spill.

Run the arithmetic once and keep the table. A Supra SB 1 with an internal box of 117 x 80 x 52 mm holds just under half a litre, so plan on about 0.36 litre. A Bull Bin 5, inside 145 x 86 x 66 mm, holds a little over 0.8 litre and plans at roughly 0.6 litre. A Rhino ARTB-05 at 95 x 89 x 43 mm is around 0.36 litre internal and plans at about 0.27. A Koala AKP-01 at 105 x 90 x 55 mm is about 0.52 litre internal, or 0.39 usable. A Panda Shelf Bin 301 at 293 x 86 x 55 mm gives 1.39 litre internal and about 1.04 usable. A Tote AK-421 at 365 x 230 x 90 mm gives 7.56 litre internal and about 5.6 usable. A Mammoth at 740 x 250 x 290 mm internal gives nearly 54 litre, of which plan on forty.

Now go back to the clip example. Five hundred and sixty clips at eleven hundred pieces to the litre need about 0.51 litre of usable space. The Supra SB 1 at 0.36 usable would need topping up three times a shift and will be the bin everybody complains about. The Koala AKP-01 at 0.39 is still short. The Bull Bin 5 at roughly 0.6 usable clears the requirement with a real margin, and that is your answer — not because it looked right, but because 0.6 is greater than 0.51. Mark the fill line physically on the bin with a strip of tape or a printed label so the standard survives contact with the shop floor.

Gloves, scoops and the size of the opening

More bins are rejected by operators over hand access than over capacity. Before you finalise a size, take the actual gloves in use — nitrile, cotton, leather rigger, cut-resistant, whatever the process demands — and have the operator pick from a filled sample. A bare hand and a leather-gloved hand are different tools, and a cut-resistant glove for a sheet metal line in Nashik adds noticeable bulk across the knuckles. The test is not whether the hand fits into the opening; it is whether the hand can enter, close around a few pieces, rotate and withdraw without scraping. If the operator has to tip the bin to get anything out, you have bought a pouring vessel, not a pick bin.

Internal proportions matter as much as internal volume here. A Hippo 612/T at 80 x 90 x 43 mm internal is a genuinely small box; with a heavy glove it becomes a tip-and-pour bin rather than a reach-in bin, which is fine for a part that is dispensed in tens but poor for one picked singly all shift. A Mammoth is the opposite problem: 740 mm long and 290 mm deep internally means reaching the back corner requires leaning in over the rim, so a Mammoth mounted above waist height is a bin whose back third will never be used. Deep or high-mounted bins want tilt access instead, which is what the Roo Tilt Bin range and its wall units exist for.

If any part is dispensed with a scoop — washers, rivets, small hardware, granules — measure the scoop before you measure anything else. The bowl of the scoop must clear the internal walls and still have room to be tilted and lifted, which usually means the internal height must be comfortably more than the bowl depth, and the internal width more than the bowl width plus a hand. The 52 mm internal height of a Supra SB 1 rules out most scoops entirely; it is a finger-pick bin. If scooping is non-negotiable, go up a range — a Bull Bin or a Tote gives the depth — and accept the extra footprint rather than issuing a scoop that cannot be used.

Making the bin fit the shelf, not the other way round

Before any of the depth arithmetic, settle one housekeeping point: confirm with the drawing or with your stockist which quoted dimension is the front-to-back length, which is the width across the shelf and which is the height. Throughout this article the quoted figures are read as length x width x height, with length being the front-to-back dimension of a front-opening bin, but a misread here means a shelf cut to the wrong depth and a purchase order you cannot use. Ten minutes checking against a physical sample is cheaper than a bay of shelving that overhangs by fifteen millimetres and fouls the aisle every time a trolley passes.

Then do the bay arithmetic. Shelving in most Indian plants comes in 300, 400, 450 and 600 mm depths. A Supra SB 1 at 125 mm outside length puts two rows on a 300 mm shelf with 50 mm spare — but the back row is unreachable unless the front row is pulled out, so treat the back row as bulk reserve, not as a pick face. A Panda Shelf Bin 301 at 315 mm outside length overhangs a 300 mm shelf and is designed for a 400 mm one, where it leaves 85 mm at the back for a stop or a label rail. A Tote AK-421 at 400 mm sits flush on a 400 mm shelf, which looks neat but leaves no finger room behind it.

Vertical pitch is where most storage volume is quietly wasted. A bin 60 mm tall sitting under a 300 mm shelf pitch means you have paid for 240 mm of air on every level of every bay. Walk one bay, measure the shelf pitch, measure the tallest bin on each level, and calculate what fraction of the bay is actually occupied. In most stores the honest answer is under a third. Panda Shelving Units and the pigeon hole units exist to close that gap, and louvre panels, rails, universal rail, stands and trolleys let the same bin size be presented at the bench without a shelf at all. Ask for the actual level pitch of any shelving unit before you assume it.

Shelf clear depth, minus any back stop, minus finger room behind the bin
Shelf clear width, divided by bin outside width, rounded down
Shelf pitch, minus bin outside height, equals wasted air per level
Whether the back row is a pick face or reserve stock
Whether a full bin can be slid out one-handed at the highest level used

Worked example one: small fasteners at the workstation

Take a sub-assembly bench in a Rajkot engineering unit with eighteen small part numbers presented on 1,200 mm of louvre panel above the work surface. The obvious candidates are Supra SB 1 at 125 x 100 x 60 mm outside, Hippo 612/T at 100 x 110 x 53, Rhino ARTB-05 at 109 x 104 x 49 and Koala AKP-01 at 130 x 105 x 60. Start with how many fit across. Twelve SB 1 fit across the panel at 100 mm each; the Hippo at 110 mm gives ten; the Rhino at 104 mm gives eleven; the Koala at 105 mm gives eleven. Eighteen parts therefore need two rows of panel whichever you choose, so the width is not the deciding factor.

The deciding factor is the largest part in the family and the fastest-moving part in the family. Work out the required usable volume for all eighteen using the pieces-per-litre and replenishment method, and look at the top of the list rather than the average. If the two heaviest movers need around half a litre usable, the Supra SB 1 at 0.36 usable and the Rhino ARTB-05 at 0.27 both fail for those two, even though they comfortably cover the other sixteen. Do not solve this by mixing four bin ranges on one panel; solve it by choosing one bin for the bench that covers your worst case and letting the small parts run under-filled.

Under-filling is cheap; mixed sizes are expensive. A bench with one bin footprint has one label position, one fill line rule, one spare bin in the drawer and one part number to reorder. A bench with four different bins acquires a fifth within a year, loses its partitions, and stops being auditable. If the volume spread across the family is genuinely too wide for one size — say two parts need five times the volume of the rest — split it deliberately into exactly two sizes from the same family, and record why. The differences between the small front-opening ranges are worth reading properly before you commit a whole plant, because the ranges are not interchangeable on their accessories.

Worked example two: a picking rack of Panda shelf bins

Now a spare parts distributor in Kolkata building a pick face for oil seals, bushes and small assemblies. The Panda Shelf Bin 301 measures 315 x 100 x 60 mm outside and 293 x 86 x 55 mm inside, which is 1.39 litre internal and about 1.04 litre usable. On a 900 mm wide shelf you get nine bins across at 100 mm each. On a 400 mm deep shelf the 315 mm length leaves 85 mm behind for a stop. At a shelf pitch of roughly 150 mm you get about twelve levels in an 1,800 mm bay, so one bay carries in the region of a hundred separate pick locations, which is the entire point of a shelf bin rack.

Run the volume check for a typical line. If the measured density is 260 pieces per litre and the item picks sixty a week against a weekly replenishment from bulk, the holding quantity is sixty plus a safety margin of about thirty, so ninety pieces, or roughly 0.35 litre. The PSB 301 at 1.04 usable is three times bigger than needed. That is acceptable and often correct: on a pick face, uniform bin size and uniform label position buy you picking speed and error reduction that outweigh the wasted cubic centimetres. Optimise volume where volume is scarce, which is line-side, and optimise consistency where errors are expensive, which is the pick face.

Two refinements are worth knowing. The transparent versions of the Panda shelf bins let a supervisor read stock level down an aisle without pulling every bin, which matters when your min/max is enforced visually rather than by a system count. And the range runs from 301 up to 606, so when a line genuinely outgrows its bin you can step up within the same family and keep the same rack, the same label stock and the same reorder discipline. Place fast movers between knee and shoulder height and push the slow, bulky ones to the top and bottom levels; a hundred locations in a bay is only an advantage if the labels are readable from the aisle.

Worked example three: totes, Bull bins and Mammoth for WIP and bulk

Work in progress moving between machines is a different sizing problem, because the bin quantity is set by the batch or the kit, not by a consumption rate. A Tote AK-421 at 400 x 255 x 100 mm outside and 365 x 230 x 90 inside gives 7.56 litre internal and about 5.6 usable. If a kit for one machine cycle is twelve sub-assemblies at roughly 0.4 litre each, that is 4.8 litre and the tote fits with a little margin. Across a 900 mm shelf you get three totes at 255 mm each with 135 mm spare; on a 1,200 mm shelf you get four with 180 mm spare, and that spare is where the route card and the job card end up living.

For heavier or bulkier line-side parts, the Bull Bin range runs from 5 up to 55, so it steps well above the small front-opening bins without changing the way the bench works. The Bull Bin 5 at 168 x 102 x 74 mm outside and 145 x 86 x 66 inside is the natural step up from a Supra SB 1 when your calculation lands between 0.4 and 0.6 litre usable, as it did in the clip example. Above that, the Mammoth at 820 x 315 x 300 mm outside and 740 x 250 x 290 inside gives close to 54 litre internal and forty usable — a genuine bulk container that will sit front-to-back on a pallet rack level of a metre depth, or one per 900 mm shelf across a bay.

The Mammoth is available as mesh and as solid, and the choice is a process decision rather than a size decision. Mesh is right where parts arrive wet from a wash line or carry cutting fluid that must drain, and where you want stock level visible from the aisle. Solid is right for small loose parts that would fall through, for anything where swarf and dust must be kept out, and where you are containing residual oil. Whichever you choose, size it so that a full one is still moveable. A forty-litre bin filled with castings from a Chennai or Hosur foundry is not a one-person lift, so plan a trolley or a crash cart at the same time as the bin, not six months later.

Partitions or simply smaller bins?

Once you have a bin size that fits the shelf, there is always a temptation to buy the larger size and divide it with partitions. Partitions are genuinely useful in three situations: when the parts are very small and the shelf face is scarce, when the part family changes frequently and you want to reconfigure without reordering, and when a set of related components must travel together as a kit. Length and width partitions, louvre panels and rails are available across the ranges, and a subdivided bin keeps one footprint, one label position and one location code while carrying three or four line items.

They are the wrong answer in one situation, and it is a serious one. If two parts in a divided bin look similar — an M6 and an M8 flat washer, two lengths of the same screw, two colours of the same terminal — do not share a bin under any circumstances. Partitions get lifted out during cleaning and put back in the wrong slot, parts bounce over a divider when a bin is slid in hard, and a mixed bin at an assembly bench produces defects that are discovered at final test or, worse, at the customer. Where misidentification is possible, use separate bins in separate locations with separate labels, and accept the extra shelf face as the price of not building wrong product.

For the extreme case of many very small part numbers, a drawer cabinet beats a divided bin. An ACO 18 component organiser measures 457 mm high, 424 mm wide and 164 mm deep, which means two sit side by side within a 900 mm bay at 848 mm, two stack within about 914 mm of height, and the shallow 164 mm depth lets them live on a narrow wall-mounted shelf or a bench back panel where a full-depth rack would not fit. One drawer per part number removes the partition problem entirely, and for electronics rework benches or a maintenance store carrying hundreds of low-value items it is usually the cheaper answer per part number.

Similar-looking parts: separate bins, always, never a partition
Kit components that travel together: partitions are a good fit
Very high part-number count, very low volume each: use a drawer cabinet
Frequently changing families: partitions, so you can reconfigure without reordering
Anything picked with a scoop: no partitions, the scoop needs the full width

Weight, stacking and the loads nobody calculates

Volume sizing gets you half the answer; the other half is mass, and almost nobody works it out. The method is simple: weigh a hundred pieces on any accurate scale, divide by a hundred to get the mass per piece, multiply by the pieces per litre, and multiply by the usable litres. That gives the mass of a full bin. Do it before you buy, because it changes decisions. The same tote that is entirely sensible for plastic mouldings can be a two-person lift when filled with brass fittings or steel turned parts, and the difference is not visible in the catalogue — it is in your own weighing.

Compare the result against two limits. The first is your own manual handling policy, which should specify what one person may lift and carry, and how far. If a full bin exceeds it, the bin is the wrong size regardless of how neatly it fits the shelf; either go smaller or plan a trolley or crash cart into the layout from day one. The second limit is the load the bin itself is rated for, and for that you should ask the stockist for the figure for the specific size and range rather than assuming that a big bin implies a big rating. Assumed load ratings are how shelves end up bowed and bins end up cracked at the corner radius.

Stacking adds a third calculation. When bins are stacked, the load passes down through the walls of the bins, not through the contents, so the bottom bin in a column carries the full weight of everything above it. Decide a maximum column height, mark it on the standard, and enforce it, because a column that is stable at three high in a Hyderabad store in January is the same column that gets built five high the week before a dispatch deadline. Also check how the bins behave empty: whether they nest or stack empty decides how much space returned bins occupy on the trolley and in the yard, and that quietly affects your internal logistics.

Environment limits that quietly rule sizes in or out

All the bin ranges here are moulded from polypropylene copolymer, carry resin code 05, and have a service range of minus ten to plus seventy degrees Celsius along with food-safe and recyclable marks. That temperature window covers the ambient conditions of essentially every shop floor in the country, including a pressing shop in Ahmedabad in May. What it does not automatically cover are the local hot spots: the bin placed at the exit of an oven or a curing tunnel, the bin standing beside an induction heater, the bin receiving parts straight off a wash line or a shot blast machine while they are still holding heat.

Hot parts are the practical failure mode. A component coming off a process at ninety degrees dropped into a polypropylene bin is outside the material's service range at the point of contact, and repeated over a shift it will distort the base. The fix is procedural, not a bigger bin: let parts cool on a rack or a metal tray, then transfer. Cold matters too, at the other end — the minus ten limit is worth checking if bins are going into a chilled room. And prolonged direct sunlight is its own issue: bins parked in an open yard in Gujarat or Tamil Nadu for months are being exposed to a UV load that nothing on an indoor duty cycle ever sees, so keep stored bins under cover.

For electronics assembly in and around Bengaluru, Chennai and Hyderabad, add one more constraint before you size anything. Standard polypropylene is insulative and will hold a charge, which is exactly what you do not want near populated boards or sensitive components, so those lines need the ESD and conductive safe range. The sizing consequence is important: the ESD range does not mirror every size in every standard range, so pick the size from within the ESD range first and then adapt the process around it. Choosing a size on a general catalogue page and then discovering it has no conductive equivalent means starting the whole exercise again.

Trial three sizes before you standardise

Never roll a bin size out to a plant on the strength of a calculation alone. Buy three sizes — the calculated one, one step smaller and one step larger — and run them on one real cell for four weeks. The reason for the two flanking sizes is that the calculation is only as good as the replenishment interval that went into it, and the replenishment interval is the number most likely to be optimistic. Running the smaller size in parallel tells you whether your milk run can actually support tighter bins; running the larger one tells you what you gain, in top-ups avoided, for the extra shelf face it consumes.

Measure the trial rather than asking for opinions at the end of it. Keep a simple tally sheet at the cell and record, per bin, the number of top-ups per shift, every stockout with the time it occurred, every overflow, and any part found in the wrong bin. Observe as well as count: whether operators are lifting bins off the panel and putting them on the bench, whether they are using two hands to scoop, whether the label is hidden once the bin is full, whether the back row is ever touched. Include the night shift in the trial, because the lighting and the supervision are different, and both change how bins get used.

Be genuinely open to the result, because the common surprise is that the smaller bin wins. Smaller bins force a disciplined replenishment loop, they free shelf face, they make stock level visible at a glance, and they make an abnormality obvious within hours rather than weeks. A bin that holds a fortnight of stock hides every problem in the supply loop behind a cushion of inventory. When the trial ends, write down the decision and the numbers behind it in one paragraph — the pieces per litre, the replenishment interval, the usable volume, the observed top-up rate — because that paragraph is the foundation of the standard you are about to write.

Top-ups per bin per shift
Stockouts, with time of day
Overflows and parts found loose on the shelf
Wrong-part events and near misses
Comments about hand access, weight and label visibility

Writing a bin standard that survives staff changes

The person who does this sizing exercise will eventually move to another company, and everything above will be lost unless it is written down in a form a new storekeeper can follow without understanding the reasoning. That document is your bin standard. At minimum it lists, for each part family: the approved bin range and size code, the outside dimensions, the holding quantity with its min and max, the location, the label format and position, the marked fill line, the replenishment trigger, and who is responsible for refilling. One page per family, with a photograph of a correctly filled and labelled bin, beats twenty pages of prose.

Add two things most standards omit. First, a rule for exceptions and a named person who approves them, because exceptions will occur and an undocumented exception becomes the new informal standard within months. Second, a master list of approved bin codes, kept short and defended, because drift is the real enemy. Somebody will always turn up with a bin from another source that is nearly the same size, and nearly is fatal — partitions, louvre panels, rails and stands are designed around specific series, and one substituted bin quietly breaks the interchangeability that made the standard worth having.

Set a review cadence — every six months, and immediately on any volume change beyond a threshold you define, or on an engineering change to the part. Tie the bin quantity to the min and max in your ERP so the two do not drift apart; a bin standard that says four hundred pieces while the system reorder point says a thousand will be ignored by everyone. And record the actual outside dimensions of your standard bins in the drawings for your shelving and racking, so that the next bay ordered, in the next factory, in the next state, is designed around the bin instead of the bin being squeezed into it afterwards.

Buying to the standard, and keeping it alive

Once the size is settled, order to the bay rather than to the part. Work out how many bins fill a bay at your chosen pitch, multiply by the number of bays, and add five to ten per cent as spares in the same order. Spares matter more than people expect: a bin will crack, a bin will be carried away by a contractor, and a new part number will appear next quarter. Buying those few extras in the original lot avoids a small top-up order later. Order the accessories in the same breath as well — partitions, louvre panels, rails, universal rail, stands, trolleys and crash carts — because they define how the bin is actually presented to the operator.

Before releasing the purchase order, get physical samples of the two shortlisted sizes and put them on your own shelf with your own parts, your own gloves and your own labels. Fifteen minutes with a real sample answers questions no catalogue page can. Shreeram Metafusion Engineers Pvt. Ltd. has been an authorised stockist of ALKON Plastics for over thirty years and holds the range at Shop-1, Gagangiri CHS, Sector 17, Vashi, Navi Mumbai, open Monday to Saturday from 10:00 to 19:00 on 93266 29967 or 98201 01937, and enquiries by email at enquiry@shreeram-metafusion.com. Ask for the sizes either side of your calculation as well; that is what makes the trial in the previous section possible.

The lasting benefit of doing this properly is repeatability. When your standard names a specific range and size from a single manufacturer's family, the bin you reorder in three years for a new line in Delhi NCR or a second unit in Maharashtra has the same outside dimensions as the one your shelving was designed around, the same partitions fit, and the same labels apply. That is worth more over a decade than any per-piece saving on a mixed purchase. The bin is the smallest unit of your material handling system, and it is the one that every operator touches a hundred times a shift. Size it once, with numbers, and it keeps paying back on every one of those touches.