Usage Tips:[6 Sizes to Meet Various Needs] The flute countersinking tool set has 6pcs drill bits, including bit diameters in 6mm(1/4), 8mm(5/16), 9mm(3/8), 12mm(1/2), 16mm(5/8) and 19mm(3/4). And length of countersink drill bit is 6.35mm (1/4 inch hexagonal handle),with 1 pcs of 5" Drilling Punch for Steel Wood Plastic.They can meet your various needs in different situations.[Premium Quality] The 1/4 hex shank countersink cutting tools are made of standard high speed steel. With high-frequency quenching for heat treatment, the HSS countersink bits have high hardness and toughness. Coated by titanium, the chamfer cutter kit is rustproof and has a long service life.[Eliminates Chatter&Vibration] The cutting edge of these woodworking drill bits is hardened and honed for sharpness. With five-flute&chatter-free design and staggered cutting teeth, these 5-blade chamfering drilling bits can provide a rapid chatter-free cutting.[Excellent Working&Easy to Identify] 1/4 inch quick change hex shank, five-blade chamfering with groove, 90 angle on the point for sharp and precise countersinking. Therere numbers on the corresponding countersink hole cutters, so its convenient for you to pick out the one you need quickly.[Widely Used] The chamfering drill bits with 5 flutes are mainly used for wood openings, reaming, chamfering, screw head and so on. Also applies to MDF, plywood, acrylic, PVC board and so on.