Alloy: Concrete drill bit is made of high cobalt , which is more advanced than YG6X, which increases wear-resistance and extra longer life span, so that the drill bits last through multiple uses Accurate and Precise: Precision unique cross angle design ground spear tip reduces bit skating and walking; superior tile cutter run through ceramic tile like butter, extremely neat and fast Size lnformation: Cement drill bit set Includes 5 different sizes: 2* 3/16” (5 mm), 4* 1/4” (6 mm), 2* 5/16” (8 mm), 1* 3/8” (10 mm) and 1* 1/2”(12 mm);easily meet variety of needs Widely Application: Tile drill bits for glass, ceramic, tile, mirror, plant pots, wood, porcelain, brick Wall, marble, thin iron plate etc; please try to keep the drill vertical and keep bits cool with a flow of cooling water; don't use on hard tile Quick Change: 1/4” Hex shank fits into all power tools more easily and securely; compatible with milwaukee and other general electric hand drill, bench drill with locking into quick change chuck 2* 3/16” (5mm), 4* 1/4” (6mm), 2* 5/16” (8mm), 1* 3/8” (10mm) and 1* 1/2”(12mm)