Litter-Robot 4 FILTERS: These cat little box filters are compatible with Litter-Robot 4 Litter Box. No cutting required, just install directly.PACK OF 10: One pack contains 10 pieces of activated carbon filters, and one filter can be used for 2-3 months, but it also depend on the actual situations. Anyway, you can simply replace it when the filter loses the effectiveness.ABSORB ODORS: Activated carbon filters can effectively absorb odors, improve indoor air quality by absorbing the peculiar smell in the cat litter box.SAFE MATERIAL: These activated carbon filters (fibrous) are made of high-quality powdered activated carbon as the adsorption material, and the high-density polymer binding material is used to attach the carbon to the fiber. With the thickness of 0.5cm (0.2"), the filters can efficiently absorb odors.EASY REPLACEMENT: The whole process takes just seconds. All you have to do is lift the lid of the litter box, remove the old filter and replace it with a new one. Pre-Cut Cat Litter Box Filter Compatible with Litter-Robot 4 Replacement Carbon Odor Filters