Zinc: For use in salt waterAluminum: For use in brackish waterMagnesium: For use in fresh waterHULL ANODES (MARTYR ANODES)SKU: 6.28309E+11$41.29PriceQuantityAdd to CartFeaturesSize6-1/4" L x 2-3/4" W x 3/4" HHole3-1/4"MaterialZinc