High Quality Material: Carbide alloy head with stronger hardness. Carbide tipped drill bits are built to last and will stay sharp much longer than typical steel drill bits. U-type slot design: U-type slot with quick dust removal, triangular handle , more stable operation. Wide range of uses: Sturdy tungsten carbide tip that can easily penetrate various materials (porcelain ceramic tiles, glass, mirrors, plastic masonry and wood). If you use the drill bits to drill concrete, brick walls and other hard materials (glass, tile, marble or granite), please use water for lubrication. 7 different sizes : 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm. 3-flat shank, these glass drill bits fit various drilling tasks perfectly, high drilling precision. Smoother rotary threading, drilling and chip removal. First-class performance: This heavy-duty tungsten carbide tipped drill bit is sharp, easy to locate, stable drilling, fast speed, won't break the edge , neat opening, smooth. The 3 flat blade shank allows you to hold it firmly, without slipping or scratching, will not damage the glaze of the tiles.