3-Piece Spark Plug Sockets provide three spark plug sockets, 5/8-inch, 3/4-inch, and 13/16-inch to ensure you always have the standard spark plug sizes. These spark plug sockets feature a rubber gasket inserted into the socket to hold the spark plug securely into place and 6 point ends to prevent round-off. They are designed with a corrosion-resistant finish and are heat treated so they last as long as you need them to. These spark plug sockets conveniently fit with your standard 3/8-inch drive. An interior rubber grommet firmly grips the neck of plugs for careful removal and installation. Advanced design grips flat sides of hex nut, not corners.