Protect propellers, shafts, engines and rudders. Complete anode kits for your specific application. Key Features Complete anode kits for specific applications Manufactured to U.S. Military specifications Prevent galvanic corrosion Kits include all installation hardware Martyr II Cadminum-free Aluminum Anodes for Saltwater and Brackish Water Used in saltwater, aluminum anodes protect better and last longer than zinc. Used in brackish water, aluminum anodes are superior to zinc which can "passivate" and not work at all or magnesium anodes which corrode too rapidly. Aluminum anodes are also lighter than zinc and contain no cadmium which is a substance of environmental concern. | Martyr Alpha I, 1991-Present, Aluminum Anodes | For Boats | by West Marine.