Doka Zinc Sea Strainer Anode | Martyr CM656934Z Traditional zinc Martyr anode protects sea strainer from corrosion in salt water. Sea strainer sacrificial anode Zinc anode for salt water applications Martyr anodes are made of a high purity specialized alloy based on the US Mil Spec Bolt-on style anode is designed to mount to hull Bolt-on style anode for sea strainers 3 1/4 in. length 1.2 in. height .45 in. thickness