Mildew stain remover plus blocker is made with a unique patented formula that removes mildew stains and provides effective long-term mold and mildew stain prevention. It is the only formula that cleans mildew stains, soap scum, and mineral deposits (like calcium and lime) and prevents mold and mildew stains from returning. It is safe-to-use indoors and outdoors on aluminum, glass, fiberglass, stone (except natural marble), cultured marble, acrylic, PVC, vinyl, porcelain, rubber, chrome, plastic, shower curtains, formica, and more. Its long-term effectiveness is not diminished by repeated washing or, for outdoor use, exposure to rain. It contains no bleaches or acids, there are no harsh toxic fumes to harm you, your family, or your pets. Biodegradable. 32 oz. spray bottle.