Diamond Coating and Nike Nickel Alloy Surface - The diamond coating can increase drilling speed and make the drill bit sharper; the nickel-plated surface can extend the service life and improve surface corrosion resistance; the thickened diamond coating on the top provides excellent cutting force for maximum drilling effect. 16-Piece Diamond Hole Saw - Comes with 16 drill bits of different sizes, including 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 35mm, 40mm, 45mm, 50mm. Laser marking makes the size clearer than other sizes and less likely to wear out. Application - Suitable for drilling glass, marble, ceramic tile, concrete block, fiberglass tile, slate marble, lightweight granite, etc. Can be used with all electric drills and impact drills. Side hole opening and laser marking - Side hole design eliminates waste and keeps the drill bit clean; laser marking makes the size marking clearer and more durable than other sizes and less likely to wear out. Note