These end caps are used for Shelf & Rod shelving only. They are used to cap the two large gauge wires that form the hang rod when installed as an 'open end'.
For every open end that you are creating you will need 1 of these open end caps, in addition to the 203 - small plastic end caps that will cover the smaller gauge wires on each shelf.
These end caps will stop hangers from falling off the end of the hang rod.