The push-back racking system is a storage stacking system with four pallets per level. Except for the last one, all of the pallets on each level are put on top of a series of carriages that slide along roller tracks when pushed.

When the aisle-side pallet is removed, since these tracks are set on a little incline with the front being lower, this allows the back pallets to move forward.

Pallets should ideally be the same reference item on each level, and they'll be handled according to LIFO principles (Last In First Out)