Cast from high quality magnesium for your 1984-1991 MerCruiser MR or Alpha One Drive (serial No. 6225577 through 0D469828). Includes trim tab anode, gimbal nut anodes and driveshaft plate anode. Designed for use only in fresh water to help protect your Alpha One or MR Drive from the harmful effects of galvanic corrosion. Easy to inspect and easy to replace. Complete attaching hardware kit 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.