Serpentine belt 865635Q01 is 2, 519 mm long to fit MerCruiser stern 496 Mag (serial No. 0W310000 and up) It is the same belt as installed by MerCruiser. See your owner's manual or service manual for specific applications. Replace worn or damaged belts to maintain proper function of engine systems driven by the belt. Easy to install using common tools. The Quicksilver brand is the leader in delivering uncompromising engine oils, parts and accessories to the marine industry for over 65 years. Quicksilver is the premier supplier of Mercury Marine original Equipment replacement engine parts, oils, and accessories, but also works to serve all original Equipment brands in the marine and powersports industries. It has earned a loyal following by providing the highest quality products that are tested through some of the most rigorous environments and testing procedures. No aftermarket company comes close to the level of research and design as Quicksilver; buying Quicksilver is buying performance, protection and peace of mind.