Martyr CMP-04, Streamlined Shaft Magnesium Anode Provides low cost cathodic protection of ocean-going vessels, structures and equipment constructed of iron, steel, aluminum, magnesium, and other metals Magnesium Alloy for use only in fresh water Only alloy proven to protect in fresh water Not recommended for use in salt or brackish water High-quality Martyr anodes are pressure diecast and manufactured to strict quality standards through an ISO 9001 Quality Management System