This is a set of eight Champion RBL11Y6 spark plugs, designed to fit Cutlass Ciera models with a voltage of 12V. These spark plugs are made of copper and have a thread diameter of 14mm, with a hex size of 16mm. They are compatible with interchange part numbers 7587, 664, and RF326, and are vintage parts that can replace 8U2J12405MA OE/OEM part numbers. The spark plugs are manufactured in the United States and come with no manufacturer warranty. They are standard configuration parts that are suitable for gasoline fuel types. The installation depth is 10.9mm (0.42\") and the parts are made of high-quality materials. This set is perfect for those looking to upgrade their ignition system and replace their old spark plugs. Representative item lot shown. Made in the USA. Packaging may vary slightly. Please review our business policies in our store for information regarding returns, shipping and warranties.