Milwaukee® Spindle Washer is designed for 4" & 5" cup wheel guards, 9" sanders/grinders, 7" heavy-duty polishers, 7" heavy-duty variable speed polishers, 7" & 9" disc sanders, 9" grinders, 7" and 9", 9" 5000 RPM sanders, 6000 RPM lightweight sanders, 6000 RPM dial speed grinders and 7", 9" polishers. Washer is made of nylon and is used to remove the threaded cup wheel from spindle.