Quicksilver 888755Q04 Alpha One Magnesium Anode Kit Cast from high quality magnesium for your 1984-1991 MerCruiser MR or Alpha One drive (serial No. 6225577-0D469828). Includes trim tab anode, gimbal nut anodes and driveshaft plate anode. Designed for use only in freshwater 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. Product Features For freshwater use only; Complete 4-piece magnesium anode kit with attaching hardware for fast and easy replacement; Cast with magnesium to meet or exceed Mil-Spec A-21412(SH) standards; Inspect anodes periodically for best protection; Produced to meet Mercury Marine original equipment manufacturer specifications to best protect your MerCruiser MR and Alpha One drive and engine; Application: Fits 1984-1990 MR & Alpha One drives (s/n 6225577-0D469828)