Professional Qaulity Core Drill Bits * Segmented design works better and lasts longer. * 40 GRIT for use with stone and glass * 10 Sizes included: 2-3/8", 2", 1-1/2", 1-3/8", 1-1/4", 1", 3/4", 1/2", 3/8", 1/4" * Note: use on a low speed with coolant (water/oil)