Material: HSS Drill 4241 Black chamfer drill body material: steel 45 Dimension: 6# 2.38mm (0.0937 inch) x 55mm(L) 8# 2.78mm (0.1094 inch) x 60mm(L) 10# 3.175mm (0.125 inch) x 63mm(L) 12# 3.56mm (0.14 inch) x 65mm(L) Shank: 1/4 hex shank.Package include4 x Countersink Drill Bits 1 x Hex Shank