Martyr Zinc, 2"shaft x 3 1/4"dia. x 2 7/8"L. The best choice for salt and brackish water.Designed for use in saltwater, these zinc anodes are composed of an alloy that meets Mil-Spec MIL-A-18001 for sacrificial anodes. This alloy is mostly zinc, but with measurable concentrations of cadmium (~0.1%) and aluminum (~0.25%). The additional cadmium causes the anode to erode from the surface inward, which causes a sandblasted” appearance to the surface. When the anode is almost dissolved, it needs to be replaced.Key FeaturesHex-head stainless steel machine screws100% circular radiusInterlocking halvesStainless steel hardwareExtra alloy around the fastenersMeets or exceeds US Military Specification (Mil-A-24779 SH)About Anodes by CMPCadmium-Free Anodes by CMPWith Martyr anodes by CMP, you can choose between traditional Zinc, aluminum or magnesium alloys. Aluminum and magnesium alloy anodes by CMP do not contain cadmium-which is a substance of enviormental concern. CMP is the only company that has the capability to produce cadmium-free anodes that perform in all three boating water types. Martyr anodes meet all US Military specifications for zinc, magnesium and aluminum alloys. Testing in an in-house facility ensures strict adherence to quality standards.Marty Zinc Anodes fo SaltwaterZinc anodes are intended for use in highly corrosive saltwater, replacing deteriorated original anodes.Martyr II Cadminum-free Aluminum Anodes for Saltwater and Brackish WaterUsed 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 III Cadmium-free Magnesium Anodes for Freshwater ONLYUse Cadmium-free, magnesium anodes if you only use your boat in freshwater. (Zinc anodes can "passivate" and stop working in freshwater.) Magnesium anodes should not be used in any other water type. If you trailer your boat, and use it in a variety of saltwater, brackish and freshwater locations, aluminum anodes are the best all-around choice for protecting your outboard or
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