Klein Tools' 32557 Interchangeable Multi-Bit Screwdrivers/Nut Drivers are heavy-duty tools designed for professionals. They are made of the highest-quality tempered steel with a torque-proof anchor in the handle. Strong, durable tips are manufactured with square edges to fit screw openings securely. They resist slippage and provide positive turning action. Stronger nut driver function improves bit-holding power, even with tough applications.