MARYKATE On & Off for Outdrives is specially formulated to clean painted aluminum outdrives, outboard lower units and propulsion components. This unique product utilizes Safe Acid Technology™ to effectively remove tough calcium and mineral deposits, scum lines, algae stains and other marine stains without harming the painted surface. Regular use will help maintain a “like new” appearance and help prevent heavy deposits from forming. May also be used to clean outboard engine covers. Safe on fiberglass. Will not harm gel coat. 15oz.