Size: each 10 pcs: 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5,5, 6, 6,5, 7, 7.5, 8 mm Each 5 pcs: 8.5, 9, 9,5, 10 mm. Ultra-hard 5% cobalt steel use on alloy & hardened steel, cast iron, titanium steel, always use a cooling agent. DIN 338 Ground 135