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.