Krud Kutter Pro Calcium, Lime and Rust Remover is a professional strength formula that breaks up heavy mineral deposits and rust stains on indoor and outdoor surfaces. Safe, fast and effective on a variety of surfaces, including showers, tubs, sinks, toilets, brick, glass, stucco, porcelain, plastic, stone, fiberglass, cement, masonry, vinyl, aluminum and more. Works quickly on the toughest stains for a professional quality clean.