39-piece screwdriver set with 1/4" ratchet and magnetic holder. For use with a drilling machine: 4 - 14mm sockets 1/4" drive (6.3mm). Includes 16 high quality alloy Allen key bits and adapters for male hex and square bits (magnet to socket adapter) and female hex and square bits (ratchet to screwdriver bit adapter) and 1.25 - 1.5 - 2.0 - 2.5 and 3mm angled Allen keys. See photo for full contents. The ratchet - the key item. Made from CrV steel in one single piece. Hardened and with perfect toothing: several of the 52 teeth engage simultaneously for transmitting extremely high torque. Quick release mechanism: releasing sockets at the push of the button. Sturdy, welded steel box, powder coated for durability. With distortion-free, indestructible trays of injected POLYPROPYLENE. Oil and acid resistant and easy to clean. With easy-to-read and durable marking of all socket sizes!