For 6 - 24mm. Including spark plug sockets 16 - 18 and 21mm. 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!