Master Mechanic, 5/16″ x 2-7/8″, Glass & Tile Carbide Tipped Drill Bit, Spear Pointed Tip Reduces Breakouts When Drilling From 1 Side To The Other, May Be Used With Any 3/8″ Drill Press Or Variable Speed Drill, Zinc Finish, Recommended For Use In Ceramic Tile, Mirrors Or Glass Of All Types, Marble, Tile, Vitrolite & China, Carded.