Double open-ended wrench, 12-piece set. forged chrome vanadium steel, matt chrome finish. heat treated and hardened to meet or exceed ansi standards for strength and durability. sizes: 6 - 7 mm, 8 - 9 mm, 10 - 11 mm, 12 - 13 mm, 14 - 15 mm, 16 - 17 mm, 18 - 19 mm, 20 - 22 mm, 21 - 23 mm, 24 - 27 mm, 25 - 28 mm, 30 - 32 mm. includes storage pouch for hanging or transporting