Nullodor crystal silica litter for cats is a new generation of litter granules the micro pored crystals absorb liquids very quickly and effectively so your cat will always have a pleasant dry litter tray and you will only have to replace the litter every 4 weeks nullodor is a 100 natural product it is compostable and neutralises bad smells in your cats litter box nullodor is made from micro porous granules with micro capillaries each crystal has an absorption rate of 150 absorbing liqu