Always check propeller clearance after installing new trim tab anodes. Aluminum for salt and brackish water, magnesium for fresh water, zinc for salt water.VOLVO PENTA™ ANODES (MARTYR ANODES)SKU: 6.28309E+11$15.59PriceQuantityAdd to CartFeaturesDescriptionSX-A/ DPS Transom ShieldMaterialAlum.Case20