What storage system utilizes slightly inclined rails to allow units to move forward when one is removed?

The push-back rack is a type of storage system designed to optimize space while providing a first-in, last-out (FILO) inventory management method. This system employs slightly inclined rails that facilitate the movement of stored units. When an item is removed from the front of the rack, the items behind it automatically move forward, allowing for easy access to the next unit.

This design minimizes the manual labor required to retrieve the products, enhancing efficiency in warehouse operations. The inclined rails help ensure that the items are pushed toward the front without any additional effort from the operator. This is particularly advantageous in environments where quick access to inventory is essential.

The other storage systems mentioned, such as FIFO rack, selective rack, and pallet rack, function differently. FIFO racks are specifically designed to ensure that the first item placed in the storage is the first one out, which does not involve inclined movement like in push-back systems. Selective racks offer direct access to all pallets but do not provide the automatic forwarding mechanism. Pallet racks, while versatile, generally require the operator to manually retrieve items from static shelving, lacking the automated push-back feature. Thus, the unique movement mechanism of the push-back rack distinguishes it as the correct answer.