We have added a medium-fine grit diamond coating to the tips of this high-speed twist drills set to drill stone ceramic glass and other hard non-metallic materials. The drills are made of superior high-grade steel. Twelve piece set includes 1 each of sizes: #36, 40, 45, 47, 50, 51, 52, 53, 54, 56, 61, and 65.
