Cobalt steel extends cutting edge life and maintains cutting life after resharpening. Automatic indexing for easy bit access and identification. Set contains the following drill bit sizes: 1/16″, 5/64″, 3/32″, 7/64″, 1/8″, 9/64″, 5/32″, 11/64″, 3/16″, 13/64″, 7/32″, 15/16″, 1/4″, 17/64″, 9/32″, 19/64″, 5/16″, 21/64″, 11/32″, 23/64″, 3/8″, 25/64″, 13/32″, 27/64″, 7/16″, 29/64″, 15/32″, 31/64″, 1/2.