The product is a set of 4 Bosch WR9DC copper spark plugs designed for various Mercedes-Benz models including the 450SE, 450SLC, 280SE, and 280CE. These spark plugs have a thread diameter of 14mm and a hex size of 21mm. They are vintage parts manufactured in Germany by Bosch Super, with a 12V voltage rating. The spark plugs have interchange numbers such as 66, BPR5EA, 67, and R45NS, and are suitable for gasoline fuel type vehicles. It is important to note that these spark plugs come with a California Prop 65 Warning for Cancer and Reproductive Harm. Exact item set is shown. New old stock with original packaging. 19mm reach. 21mm hex. Set weight 9 oz. Made in Germany. No returns on installed items or partial sets. Please review our business policies in our store for information regarding returns, shipping and warranties.