K Tool International impact sockets are forged from the finest chrome-moly steel which provides the best strength and durability. Sockets are designed and crafted to take on the toughest jobs with solid performance. Lifetime warranty. All sockets are marked with part number and size for ease of use. Features and Benefits: * Chrome moly * Thin wall * Heat treated * 9 Sockets: 3/8 thru 7/8 in box.