The Grey Pneumatic 1155TT is a 3/8-inch drive impact socket featuring a TT55 tamper-proof (or security) Torx bit. Engineered specifically to withstand the high torque of impact tools, it is constructed from forged chrome-molybdenum alloy steel and finished with a black oxide coating for maximum durability and corrosion resistance. Key details: Drive Size: 3/8"Bit Size: TT55 (Tamper-Proof Star) Overall Length: 1.97"Material: Chrome-Molybdenum Steel