This listing is for a set of 4 Autolite 86 spark plugs suitable for use in 1986-1988 Mazda RX7 vehicles. These spark plugs are made of copper and have a thread diameter of 14 mm and a hex size of 21 mm. They have been manufactured in the United States and are vintage parts. These Autolite spark plugs have interchange part numbers of AR52, RJ14YC, R45S, and RJ14Y and an OE/OEM part number of N3X418110. They are designed to operate on a 12 V voltage and can be installed up to a depth of 3/8 in. This set of spark plugs is ideal for ignition systems and components and can be used in various car and truck parts and accessories. Exact item set is shown. New old stock spark plugs with original packaging. Made in USA. No returns on installed items or partial sets. Please review our business policies in our store for information regarding returns, shipping and warranties.