Designed specifically for underwater use like on a Max-Prop. PYI's testing has found this product to perform well in many water conditions around the world. Zinc Coat is for use only on bare metals such as steel, stainless steel, cast iron, copper, nibral, bronze, galvanized steel and lead. It forms an excellent adhesive bond to underwater metals and running gear and inhibits corrosion on these surfaces. Because of its smooth, hard surface it will self-clean in service. Note: Do not apply antifouling paint over Zinc Coat. Do not apply on the end cap of the Max-Prop where the sacrificial zinc anode makes contact. This product can only be shipped via Ground transportation.