Thin walled spark plugs, sizes: 14mm (O.D 18.8mm), 16mm (O.D 20.8mm), 18mm (O.D 23.9mm), 19mm (O.D 24.8mm) and 21mm (O.D 26.8mm) x 3/8"D. Socket length: 65mm x 6 point (single hex) profile. Fitted with rubber inserts to protect and retain the spark plug. Supplied in a blow moulded storage case. Manufactured from chrome vanadium with satin finish.