High Quality Multipurpose Drill Bits: Tungsten Carbide Tipped for Longer Life Special: The U-type slot with dust collection, the 3-flat shank allows the drill bit to be held firmly and stably in an electric drill. Cut Perfect Circles Holes: Suitable for glass, ceramic tile, wood, ceramic, stone, concrete, brick, etc. When drilling hard materials (glass, porcelain floor tiles, marble or ), please use for lubrication, perfect for drilling holes in bathroom tiles or wall mirrors. Once drilled through the tile or mirror, the drill bit easily fits into the masonry behind Product cannot be used to drill tempered glass and pure concrete. When drilling, only use the flat perforation function, do not exert impact force, When drilling fragile objects, the drilling speed is not too high, the pressure should not be too large, so as not to damage the drilled objects Color: Black + Silver Material: Tungsten Carbide Size: Blade Diameter 18mm 8mm 10mm 12mm Package Contents: 18pcs x Ceramic Tile Drill