Step drill bit, material cobalt, steam oxide finish, number of hole sizes 8, shank size 7/16" step thickness 1/8" size range 9/16" - 1". Sizes included 9/16", 5/8", 11/16", 3/4", 13/16", 7/8", 15/16", 1", number of flutes 1, shank type hex, bit length 3"