... following size:Sizes: 4-12 mm step: 4, 6, 8, 10, 12 mm 40-20 mm step: 4, 6 ... 16, 18, 20 mm 5-28 mm step: 5; 8.8, 11.8, 15.3, 19, 24.5, 28 mm 40-30 mm ... step: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 ... , 24, 26, 28, 30 mm 4-39 mm step: 4, 6, 9, 12, 15 ... with 1/4" quick change hex shank or 3/8" quick change hex shank prevents slipping in drill chuck ...