General description A three-piece universal joint, Bi-Hex (12pt) 3/8" drive socket set designed for accessing awkward spark plug recesses commonly found in modern vehicles. This professional quality set includes sockets for all common plug sizes: 14mm, 16mm, and 21mm. Technical specifications Socket sizes: 14mm, 16mm, 21mm Drive size: 3/8" Length: 100mm Material: Chrome vanadium Usage Ideal for removing and installing spark plugs in modern engines Universal joint design allows for angled and difficult access Rubber inserts protect and securely hold the spark plug