The Mac Tools 9-pc Spark Plug Socket Set, No. SPK9-SET, offers a complete collection of tools in one package for added convenience in servicing spark plugs. Included in the kit are three different sizes and three unique configurations to match 9/16", 5/8" and 13/16" spark plugs in standard, universal and extra deep styles. The sockets feature a chromed finish for added corrosion protection, and each socket is knurled for easier hand turning. The set also comes in a heavy duty blow molded storage case.