High quality carbon impregnated polyester insert removes odours from the litter pan. The highly active carbon pad's large surface area traps odours passing through the filter, keeping the litter pan smelling fresh and clean. Catit Hooded Cat Pan Replacement Carbon Filters are for use with: Catit SmartSift Catit Hooded Cat Pans Catit Jumbo Hooded Cat Pans Catit Style Jumbo Hooded Cat Pans Available Size: 2-Pack