Crescent Metric Combination Wrenches are made from chrome vanadium alloy steel that has been heat-treated for maximum strength and long-lasting durability. They have been coated with a nickel chrome plating and buffed to a mirror polish finish. Surface drive® technology on box-end virtually eliminates fastener rounding. Sizes have been stamped on both sides for easy identification. CCWS1: 6 Piece: 8, 9, 10, 12, 13 & 14mmCCWS3: 10 Piece: 8, 9, 10, 11, 12, 13, 14, 15, 17, 19mmCCWS5: 15 Piece: 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 & 21mmThe Crescent CCWS5 Metric Combination Wrench Set of 15, contains the following: Sizes: 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 & 21mm