XIANQI VERSATILITY – Comes in 5 most popular sizes bits 1/4, 3/8, 1/2, 5/8, 3/4 inch counter sink drill bits. PRECISION - 82-degree tip drills countersink holes into most machinable metals, plywood, softwood, hardwood, fiberglass plastic, mild steel, don't work on stainless. COMPATIBILITY – 1/4” round shank fits all handheld and stationary drills. EFFICIENT- Five-flute design reduces vibration and removes chip better, provides smoother drilling experience and extended bit life. DURABILITY - Made from High-Speed Steel with golden oxide finish for corrosion resistance. Product Description： The Countersink Drill Bit Set made from industrial grade high-speed steel for increased durability, each countersink has a golden oxide coating to resist corrosion and a five-flute design removes chips faster and dills smoother and ensures an extended life. It features precision ground 82° tips for countersinking most machinable metals, wood, and plastic.; Each set includes 1/4", 3/8", 1/2", 5/8", and 3/4" countersinks,;