Industrial 7172221 Spark Plug Socket Three Eighth Inch Clip 21mm

SONIC 7172221 Spark Plug Socket is a 3/8" drive, six‑point hex socket sized for 21 mm spark plugs, designed with an inner retaining clip to hold the plug securely as you remove it from the cylinder head. This tool is milled from chrome‑vanadium steel for durability and long service life, and it combines compact overall dimensions (length about 65 mm; height 21.7 mm; width 21.7 mm; outer diameter 22 mm) to fit into cramped engine bays. The 21 mm hex size matches a common class of plug sizes used across many engines, and the clip design helps prevent dropping the plug during extraction, a frequent workflow advantage on lift stands and in confined spaces. Compatible with standard 3/8" drive ratchets and extensions, this socket is intended for use in automotive maintenance and repair tasks that involve 21 mm spark plugs, providing a reliable grip without slippage during installation or removal. As part of Sonic’s range of spark plug sockets, the 7172221 offers a precise, metric-size solution for professionals and DIY techs who service vehicles that specify a 21 mm plug size.