These bushing will allow you to install different size tools into our handles. You can have a handle with a 5/8" receiver, put a 5/8" to 1/2" bushing in the handle and be able to use both 5/8 and 1/2 inch tools in the same handle. The 1/2" to 3/8" bushing allows you to use 3/8 inch tools within our 1/2" receiver handles.
(Picture shows two different sizes - actually sold as a single item.)