The OEMTOOLS 3/8 Inch Drive Magnetic Spark Plug Socket Extension (9/16 Inch) is made with a Hard Chrome™ Finish that is easy to clean and keeps away rust. The sockets are made with special alloy steel, which is heat-treated for extra strength. The chamfered ends on bits and sockets make fastener engagement quick and smooth. The Spark Plug Sockets are magnetic and won't wear out or be damaged by oil.