The Benro 82-58mm Step Down Ring is designed for use with the Benro FH100 filter holder in combination with 82mm adapter ring. It allows you to attach your filter holder to lenses with 58mm diameter screw thread mount. This stepping ring is an alternative to purchasing 58mm adapter ring for the 100mm system, and instead allows you to 'step down' to use your 82mm adapter ring with lenses sized 58mm. When used in combination with a 82mm adapter with the 100mm system, it will allow the system to be used with lenses sized 58mm.