Rust Stain Remover is the best way to eliminate unsightly rust stains from boats, RVs, exterior walls of homes, or wherever else they may form. The formula begins working on contact, dissolving the oxidation that causes these stains. Easy to use formula can be sprayed directly onto stained area and rinsed off with no heavy scrubbing needed. Also great for cleaning corrosion stains caused by metal hardware, nuts, bolts, and other marine fittings. Contains no harsh chemicals or acids.