5 essential-size twist bits tipped with polycrystalline diamond - hardest cutting material available * Heat-resistant high speed tool steel shank; polished chrome finish reduces resistance * Diamond particles permanently brazed 1/2" of tip and cutting edges; fit all 3/8" & 1/2" drill chucks * Preferred drilling tool for glass, stone, tile & hardened steel; use with power drill or rotary tool * 1/16(1.5mm) x 1-3/4, 3/32(2.4mm) x 2-1/4, 1/8(3.2mm) x 2-1/2, 1/4(6.5mm) x 4, 3/8(9.5mm) x 5"