Hagen Catit Magic Blue refill pads absorbs and retains up to 80% of ammonia and reduces fecal odors by an average of 40%, depending on your cat's cat food diet Includes filter cat litter pads for 3 months, for use with the Catit Magic Blue Cartridge (sold separately), a reusable holder that fits every cat litter box Safe and easy to use in any cat litter pan, the pads are also non-toxic and unscented Hagen Magic Blue refill pads absorbs hazardous ammonia gases found in cat litter 25 times more effectively than carbon-based filters Perfect to use with Catit Magic Blue for better air quality for you and your cat