Quicksilver 57-865615Q03 Serpentine BeltGenuine OEM Mercury-Mercruiser part. Direct replacement serpentine belt for Mercruiser Stern Drives. Belt is 704 mm long and is easy to install.Fits: 350 MAG MPI Alpha/Bravo; 350 MAG MPI Alpha/Bravo EC; 350 MAG MPI Horizon Alpha/Bravo EC; 377 MAG MPI Bravo; 377 MAG MPI Bravo EC; 383 MAG Stroker Bravo; 383 MPI FWC Bravo; 383 Stroker Scorpion Bravo; 385 Performance Tuned; 4.3L MPI Alpha/Bravo; 5.0L MPI Alpha/Bravo; 5.0L MPI Alpha/Bravo EC; See your owner's manual or service manual for specific applications.Interchangeable Sierra Marine: 18-15100;