Catit Magic Blue Refill Pads Magic Blue absorbs and retains up to 80% of ammonia and reduces fecal odors by an average of 40%, depending on your cat's diet Includes filter pads for 3 months, for use with the Magic Blue Cartridge (#44305 - available separately), a reusable holder that fits every litter box Safe and easy, non-toxic and unscented Magic Blue absorbs hazardous ammonia gases 25 times more effectively than carbon-based filters! Use Cat it Magic Blue for better air quality for you and your cat!