Diamond Coating and Nike Nickel Alloy Surface - Diamond coating can increase drilling speed and make the drill bit sharper; Nickel plated surface can extend the service life and improve the corrosion resistance of the surface; Thickened diamond coating on the top can provide excellent cutting force to achieve maximum drilling effect. Saw - 16pcs Diamond Hole Saw - comes with 16pcs drill bits in different sizes including 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 35mm, 40mm, 45mm, 50mm. Laser marking, the size is clearer than other sizes, not easy to wear. Application - Suitable for drilling holes in glass, marble, ceramic tile, block pot, fiberglass tile, slate marble, light granite, etc. Used with all electric drills and impact drills. Side hole opening and laser marking - Side hole design can avoid waste and keep the drill bit clean; laser marking, the size marking is clearer and more durable than others, not easy to wear. Note: Do not use it on concrete