Zep Pro-Strength Toilet Bowl Cleaner dissolves limescale, rust stains, and tough buildup inside toilet bowls, urinals, and bidets. This fast-acting formula begins working quickly and clings to surfaces for effective cleaning. It is safe for use in septic tanks, drain lines, and water treatment systems when used as directed. The angled neck bottle allows for precise application under the rim and into hard-to-reach areas, improving overall cleaning coverage.