Martyr anode kits protect outdrives against galvanic corrosion.Made of aluminum alloy, these anodes are your best choice for salt- or brackish water. Kit includes oneCM3855411anode and one CM3854130 anode. Kit includes mounting fasteners.Key FeaturesDesigned to fit Volvo SX outdrivesAluminum anodes for use in salt- or brackish waterKit includes one CM3855411collar anode and one CM3854130bar anodeFasteners includedAbout Aluminum AnodesUsed 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.