... Drill Bits---Diameter: 51mm to 127mmThread Type---R22,R25,R28,R32,R38,T38,T45,T51Face Shape---Plate, Concave, Convex.Bit Shank & Coupling ... ---Suitable for medium-hard rock (1033.5bar~2067bar)Plate ---Suitable for had rock ( more than 2067bar)Drill RodSteel Drill Rod---H19/H22, Length ... Thread Rod---R25,R28,R32,R38,T38,T45,T51. Integral Drill Rod---H19/H22, Diameter---20mm - 42mm. rock drill bits