What is a crash-lock bottom?

The alternative is a tuck-in base, where whoever packs the product has to fold four flaps in sequence for every single box. On a hundred units that is a mild irritation. On tens of thousands it is a measurable labour cost, and it is the reason crash-lock exists.

The trade-off is at the other end of the process. A crash-lock base needs a more complex die, more glue lines and a folder-gluer capable of the fold, so the unit cost is higher than a plain tuck-end carton. Whether that is worth paying depends entirely on what your packing operation costs — which is why it is worth telling us how the box will actually be filled.

Structurally the locked base is also stronger than a tuck-in, because the flaps interlock rather than simply resting against each other. That makes it a sensible choice for heavier products, bottles and anything that will be carried by the box rather than in a bag.

It is a common construction for takeaway food boxes, bottled products, and anything assembled at speed on a counter — and it is one of the standard templates in our dieline library.

Where it is not worth it: small, light products whose base is never really under load. There the locked base is board and glue you are paying for on every unit, and a plain tuck-in costs less and takes no meaningful time to fold. The decision should follow the weight of the product and the volume of the packing operation, not the look of the drawing.