Cast in aluminum for 135-200hp 4-cylinder Mercury Verado outboards and 75-115hp and 135-250hp OptiMax outboards. Designed for use in freshwater or saltwater to help protect your outboard from the harmful effects of galvanic corrosion. Easy to inspect and easy to replace. Attaching hardware and instructions included. 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.