Unique deactivated acid activates on contact with soil for safer scale remover with a health rating of 1 in use. Kicks soils like an acid to remove built-up hard water scale, rust, soap scum, mold stains and mildew stains. Use on sinks, toilets, urinals, water fountains, showers, tubs, tile, grout, glass, copper, brass, fiberglass, and stainless steel.