The product is a genuine BMW OEM mechanical belt tensioner, specifically designed for the R55, R55N, R56, R56N, and R57 models. It has a manufacturer part number of 11287571015 and is made in Germany. This high-quality belt tensioner ensures proper tension and performance for your BMW engine, with interchange part numbers including Cooper, Cooper S, Cooper SX, Cooper X, JCW One, and various Eco models. Upgrade your vehicle with this reliable and authentic BMW part to maintain optimal engine functionality.