4 Replacement Carbon Booster Filter For Holmes Total Air Purifier Aer1 Series HAP242-NUC I Filter AOR31 A pack of 4 premium carbon pre filter absorbs and eliminates any household unfavorable odor For use with Holmes air purifier models: HAP2400, HAP242, HAP9240, HAP9242, HAP412, HAP9412 and HAP9414 requires 1 filter. HAP422, HAP424, HAP9422 and HAP9424 requires 2 filters 9.5in (L) x 4in (W). Cannot be used independent of the main purifier filter. A pack of 4 pre filters included. Directly apply to the Aer1 filter Premium Carbon Filter absorbs and eliminates odors that come from pets, nurseries, kitchen, garbage, or litter boxes. colour: black Material: sponge Package Contents: 4 * carbon spray sponge Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.