MATERIAL---Using high quality diamond, the drilling ability was better the drill hole more accurate. 16 PCS DRILL BITS---Comes with 16 PCS of different sizes of drill bits including 6mm 8mm 10mm 12mm 14mm 16mm 18mm 20mm 22mm 25mm 28mm 30mm 35mm 40mm 45mm 50mm WIDE USE --- Widely used in glass, ceramic, marble and other hard brittle materials. DURABLE --- The drill bits are made from a diamond coating, which is excellent for making precise, smooth holes in glass or other fragile hard materials. NOTE --- By reducing the drilling speed and continuing to add water cooling to extend the life of the drill bits (dry drilling is strictly prohibited). Excellent for making clean and precise holes on glass, tiln, fine ceramics, wood or other. Works well with common electric drill, bench drill. Usage: 1. Clean the surface and keep it wet with water and coolant. Then mark the position of the drill hole. 2. Start drilling slowly at a 45 degree angle to the surface. 3. Drill at low speed and adjust the drilling angle to a vertical position when the hole appears. 4. Slow motion to drill the hole directly or you can step out and drill from the other side to make it smooth. Diamond hole saw Reducing the drilling speed and continue to add cooling water to extend the life of the drill bits (dry drilling is strictly prohibited). Note: Drill at a 45 degree angle to start the hole at low speed, then position vertically once the hole is started. Nickel plated surface and decrease cutting resistance. Large cutout for better ejection. Features: 1. Dimensions: hole diameter: 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 35mm, 40mm, 45mm , 50 mm Weight: 310 g Contents: 1 set of 16 diamond drill bits