Our 3/8" Drive 18mm 6-Point Spark Plug Socket features a durable dual-material rubber retainer designed to maintain a more secure fit within the socket while securely holding onto spark plugs to avoid dropping or damaging. A precision knurling on the outside of the socket allows for better control when hand tightening or loosening. Both the socket and retainer withstand harsh chemicals commonly found in the garage. Stamped size markings make it easy to identify the size of the socket. The external hex at the base of the socket fits a 20mm wrench for added control. Our Spark Plug Sockets are backed with a Lifetime Guarantee.