Excellent quality, made of tungsten steel and heat-treated. High hardness, sharp edge, high precision, smooth cut, impact resistance, high toughness. The curved design of the drill bit allows for chip removal and is more efficient at drilling. The 6-size set includes 30/35/40/45/50/60 mm. Suitable for pistol drills, bench drills, portable electric drills, hand-held electric drills, motorized drilling machines, and magnetic belt drills, etc. Widely used for drilling precise, chip-free, flat-bottomed holes in any thickness of softwood. Perfect for fitting ball joint door studs, drawers; drilling into wood products, plastic products, wood and plywood, etc. Easy to store and select. Each drill bit comes in its own plastic box, and the size is indicated on the box, so you can get the right drill bit from the shelf in seconds.