From the Manufacturer16MM Plug Socket Features KD Tools plug socket is perfect for anyone who works on engines can appreciate this innovative socket design. A magnetic core holds drain plugs in the socket while drain plugs are being removed. Anodized, aluminum sockets are color-coded so its easy to find the right size. The knurled speed ring makes installing and removing sockets from your ratchet handle quick and easy. Serrated edges provide added grip for hard-to-reach fasteners. Sockets fit standard 3/8 ratchet drives and GearRatchet hand