Zinc: For use in salt waterAluminum: For use in brackish waterMagnesium: For use in fresh waterHULL ANODES (MARTYR ANODES)SKU: 6.28309E+11$29.09PriceQuantityAdd to CartFeaturesSize8-1/2" L x 3-5/32" W x 1/2" HHoleN/AMaterialZinc