A must to properly install harmonic balancers or drive pulleys that are pressed on one(1) or two(2) groove pulleys on the crankshaft. Thread Adapters, Jam Nut (black knurled, under bearing in photo),Center Screw, Hex Nut, Thrust Bearing and Instructions Included.Use with Cal Van 189, Harmonic Balancer Puller/RemoverSizes:M12-1.75, M12-1.5, M10-1.5, M14-1.5, M15-1.5, M16-2.07/16-20, 1/2-20, 9/16-18, 5/8-18, 3/4-16