Stamped and ink filled diameter markings for wear resistence, it helps you select the size easier Constructed from heat-treated, impact grade Chrome Molybdenum Steel, with a protective black phosphate coating Set Includes: 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 32mm, 33mm, 34mm, 35mm, 36mm It comes with a sturdy and convenient storage case. Keep each piece in the proper position All EMENTOL products meet or exceed ANSI performance standards Stamped and ink filled diameter markings for wear resistence, it helps you select the size easier. Constructed from heat-treated, impact grade Chrome Molybdenum Steel, with a protective black phosphate coating. It comes with a sturdy and convenient storage case. Keep each piece in the proper position. All EMENTOL products meet or exceed ANSI performance standards.