●1. Premium Countersink:Made of 4241 steel,titanium coated,sharp blade,remove burr without leaving scratches,great for 90 degree hole drilling in carbon steel,stal,thin iron plates,insulation board,PVC board,aluminum,soft and hard wood,plastic ●2. Six different diameters: 6mm, 8mm, 9mm, 12mm, 16mm, 19mm. Handle Diameter: 6.35mm For daily use. ●3. The bits are standard size and are compatible with all standard drills, including floor drills. ●4. SHARPER & HARDER: The drill bits are made of heat treated carbon steel blades and ensure a long service life. With titanium against rust, use in material HRC below 25 ●5. 3 flutes 90 degree bits: more concentric, effortless to use and more durable. 90 degree angle at the tip for sharp and precise hole milling, for precise holes.