Martyr CMALPHAKITA Aluminum Alloy Merc Alpha Gen II Mercury Anode Kit  Aluminum Provides low cost cathodic protection of ocean-going vessels, structures and equipment constructed of iron, steel, aluminum, magnesium, and other metals Includes all necessary anodes, hardware and install instructions for easy underwater installation Aluminum Alloy for use in salt & brackish (mixed) water Protects 50% longer than traditional zinc anodes Contains no Cadmium, making it environmentally friendly