... famous drilling machine, such as Atlas Copco, Sandvik, Ingersoll- Tapered Drill BitType --Chisel Bits / Cross Bits / Button Bits ... R38,T38,T45,T51Face Shape---Plate, Concave, Convex.Bit Shank & Coupling sleeve---R22,R25,R28,R32,R38 ... /110MM 3) Face ShapeConvex---Suitable for soft rock ( less than 1033.5bar)Concave---Suitable for medium- ... Rod---H19/H22, Diameter---20mm - 42mm. rock tapered chisel bit