1.Long-life, 2.High penetrability. 3.Can match many famous ... of the products.Tapered Drill BitType --Chisel Bits / Cross Bits / Button Bits Diameter---28mm,30mm 32mm,34mm,36mm,40mm,42mm,44mmThread ... T38,T45,T51Face Shape---Plate, Concave, Convex.Bit Shank & Coupling sleeve---R22,R25,R28,R32,R38,T38,T45,T51Down-The-Hole ... Integral Drill Rod---H19/H22, Diameter---20mm - 42mm. T51 Thread button bits