SK Hand Tool 4478 9/16-Inch Drive Spark Plug Swivel Socket, 3/8-Inch, Chrome Sockets are manufactured to rigid specification in a variety of sizes and styles to ensure you always have the right tool for each application Design drives the side of the fastener, not the corner, to provide increased strength and avoid rounding of rusted or damaged fasteners High polish SuperKrome plating results in a jewelry-like finish providing long life and maximum corrosion resistance