Premium CR-MO? Made of premium impact grade chrome molybdenum steel construction with black phosphate finish. Set Includes? 4 x 3/8 Dr. Extension Bars- 3″, 6″, 10″, 15″, 1 x 3/8Dr. Impact Universal Joint, 1 x 1/2″ to 3/8″ Adapter, 9x Star Sockets and 9 x Inverted Star Sockets. Set Includes? 3/8 Dr. Deep/standard in SAE and METRIC from 6mm to 19mm, 1/4-Inch- 3/4-Inch, 3/8Dr. Universal Sockets in SAE and METRIC from 10mm to19mm, 3/8-Inch – 3/4-Inch. High-torque? Radius corner design, 6-point opening reduces wear and increases torque on fasteners by placing force on fastener walls rather than fastener corners. Service Guarantee? All Tools meet or exceed ANSI performance standards. It comes with 1 year quality guarantee.