Classic High Speed Steel (HSS) construction with a titanium coating provides ultimate durability and longer drill bit service life through multiple uses without deformationThe cutting edge is hardened and honed for sharpness and features a chatter-free design with staggered cutting teeth to ensure precise countersinking and clean, smooth holesSizes: 28 x 3/64", 27 x 5/64", 20 x 1/8", 10 x 5/32", 12 x 3/16", 8 x 15/64", 8 x 9/32", 3 x 5/16", 2 x 23/64", 1 x 1/2", 27 x 1/16", 27 x 3/32", 20 x 9/64", 10 x 11/64", 10 x 7/32", 12 x 1/4", 2 x 19/64", 2 x 21/64", 1 x 3/8"