This potent formula, known as Skilcraft Calcium Lime Remover, effectively eliminates stubborn mineral deposits and eliminates unsightly rust stains. It can be used on a variety of surfaces such as tubs, shower heads, glassware, sinks, fiberglass, humidifiers, and dishwashers. With a USDA Certified Biobased seal, this product is made with highly efficient ingredients, providing an eco-friendly solution to combat hard water stains, rust build-up, and more.