Katfresh litter box odour filter is the ideal way to keep the air around the litter box clean and odour-free. Thanks to the granulate bags in the deodorizer, bad odors and ammonia odors are absorbed and you keep the air clean. The Katfresh litter box filter keeps the litter box odour-free for one month. One package contains a box and two bags of granulate. The bags should both be placed in the box and then the box can be stuck in its entirety into the lid of the litter box.