This 5pcs countersinks are not suitable for drilling less than 25HRC hardness workpieces, such as iron sheet, carbon steel, PVC board, wood, insulation board, etc.? Features?:? 6 pcs includes 5 bits for drilling pilot holes for screws sizes #5 #6, #10 and #12 and #8, 1 wrench hexagonal. Specially designed countersinks made of HSS steel counter bores & counter bores. Adjustable counter sleeve depth with an allen key. Adjustable length drill bits for screws different lengths simply by loosening the clamping screw. Pre-drilling and countersinking to drive screws flush with the surface material or deep boring counter hole for screw heads below the pipe surface. Super sharp cutting flute effectively clears chips and leaves a clean & smooth hole. Adjustable drill bit length for desired screwed depth and features a flattened shank for slip-free countersinking connection. /> Specifications?:? Color?: Gold + black? Material?: Carbon steel + high speed steel? Hardness?: HRC 60? Countersinking sizes?: #6, #8, #10, #12, #14? Stem?: 1/4" hex shank? Quantity?: 5 pcs with drill bits + 1 pc small wrench? Chamfer diameter?: 10mm/0.39"? Countersink diameter?:? 6# 2.38mm/0.09"? #8mm 2.78/0.11"? 10# 3.175mm/0.125"? 12# 3.56mm/0.14"? 14# 3.97mm/0.16"? Order weight day?: About 58.5g/2.06oz?Package Size?: Approx. 7 * 5 * 1.1 cm / 2.78 * 1.97 * 0.43 in? Package weight: About 60g/2.12oz?