Catit Magic Blue is safe, easy, non-toxic and unscented. The Catit Magic Blue Refill Filter pads are to be used with the Catit Magic Blue Cartridge to successfully reduce hazardous ammonia gases up to 80% and fecal odors by an average of 40%. The Catit Magic Blue Refill Filter pads include 6 pads (3 months supply). The Catit Magic Blue Cartridge is available separately (44305W). For a free reminder to replace the filter pads, visit https://www.catit.com/magic-blue-replacement to sign up. Visit catit.com for more information.