15 different sizes of diamond bits: 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 35mm, 40mm, 50mm. Suitable for drilling holes in glass, tile bottles, jars, ceramic fiberglass porcelain tiles, slate marbles, light granite stone (especially for glass AND tiles). The hole saw opens smoothly, no suffocation, no broken edge, no shaking phenomenon, the hole speed is very fast, easy chip evacuation and so on. Slow drilling speeds, low drilling pressure and more use of water lubrication will greatly extend the life of the drill bit. Simple operation: Draw a circular path. At the beginning, slowly drill at a 45° angle (no vertical drilling is allowed!) after a fixed position appears, then slowly keep the machine and objects horizontal.