There are tapered button bits and threaded button bits two types including button bits, retrac button bits, drop centre button bits, drop centre retrac button bits, all steel button bits,etc. Diameter (mm)=32, 38, 40, 41, 42, 43, 44, 45, 46, 48, 51, 54, 55, 57, 60, 64, 65, 70, 73, 75, 76, 80, 89, 102, 115, 127 Socket dia.(mm)=22, 24, 25, 32, 38 Taper 4.8 6 7 11 12 Connect threads of R22, R25,R28,R32, R38,T38, T45, T51