This set of Autolite 55 spark plugs is perfect for vintage car enthusiasts who want to keep their ride running smoothly. With a 14 mm thread diameter, 21 mm hex size, and 12 V voltage, these spark plugs are a great fit for many AMC, Chrysler, and Triumph models. Made of high-quality copper material, these spark plugs are built to last. They also come with a vintage look that adds a classic touch to any engine. In addition to the standard configuration, these spark plugs have interchangeable part numbers such as C44NS, 00910020016, 44XL0, AG42, 44XLS, N13Y, 44NS, and N12Y. The installation depth of 19 mm ensures a secure fit, and the spark plugs are manufactured in the United States to ensure the highest quality standards. Don't miss out on this opportunity to add a touch of vintage style to your engine with the Autolite 55 spark plugs.