Metal crates, also known as steel bins, metal logistics boxes, the bottom of the frame-type rigid structure, welded from steel panels and steel legs. The bottom frame is often made of rectangular tube, square tube through welding, and the columns are usually made of square tube or angle steel.

For the existing collapsible metal crates, the way through the stack to stack each other high, multi-storey storage, three-dimensional storage, the formation of three-dimensional storage capacity, without the need to resort to shelves and other equipment. However, more than one metal crate stacked, how the upper and lower two layers of metal crate column docking is not in place, there is an impact on the overall stability of the problem, and the upper and lower two layers of the stacked structure does not have a positioning structure for rapid positioning between each other.