These patented birdbath water cleaners contain all-natural beneficial bacteria and enzymes that help prevent stains, mineral deposits and organic buildup. Each disposable floating dispenser treats up to 7 gallons for 30 days. Safe for humans, birds, pets, fish and plants. For best results, start with a clean birdbath. Do not allow dispenser to dry out during use. Four dispensers provide 120 days of treatment. Made in USA.