Historical
ISO 22977:2005
Road vehicles - M12 x 1,25 spark-plugs with flat seating and 14 mm bi-hexagon and their cylinder head housing
ISO 22977:2005 specifies characteristics of M12 x 1,25 spark-plugs with flat seating and 14 mm bi-hexagon and of their cylinder head housings, for use with spark-ignition engines.
International Organization for Standardization [iso]