Replaces standard 5/8-11" flanges on grinders, to enable fast tool-less disc change; using built in thumb flange No need for pin spanner anymore, change discs in less than 12 seconds This part Compatible with all 4", 4-1/2", 5", 7" and 9" grinders that have a 5/8-11" threaded shaft and also Compatible with Dewalt, Makita, Bosch, Hitachi, Metabo, Milwaukee