4.36 inch x 1.92 inch Zinc Hull Anode | Martyr CMM24 Oval zinc Martyr anode protects boat's hull from corrosion in salt water. CMM24 sacrificial anode Zinc anode is for use in salt water 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 4.36 in. length 1.92 in. width .7 in. thickness 1.25 in. bolt hole center to bolt hole