Use either of these adaptors to turn your 4-1/2" angle grinder into a Valve Seat Grinder. Both adaptors have 5/8" x 11 threads to fit most popular angle grinders. Choose from two models - one with a star-drive for use with Sioux-Style drivers and one with a hex-drive for use with Kwik-Way Style drivers. Both adaptors are 1-1/2" OAL.