TEKTON SHB91317 3/8 in. Drive Hex, Torx, TR Torx, Phillips, Slotted, Square Bit Socket Set (110-Piece)TEKTON heat-treated S2 steel bits are press-fit into the socket for a straight, tightly mated fit that cant loosen over time or under stress. The tips are machined to exact tolerances for precise engagement with fasteners. Large, stamped size markings are permanently impressed into the material by a roll-stamp die. Detent grooves and beveled edges provide a smooth and secure connection with the drive tool. Sturdy, clearly marked storage case is made from high-density polyethylene material that withstands exposure to common lubricants, fuels, and solvents.