set2: 3 x filter + 4 x carbon spray spongeA pack of 4 premium carbon pre filter absorbs and eliminates any household unfavorable odorFor use with Holmes air purifier models: HAP2400, HAP242, HAP9240, HAP9242, HAP412, HAP9412 and HAP9414 requires 1 filter.HAP422, HAP424, HAP9422 and HAP9424 requires 2 filtersWorks for Holmes air purifier filter AER1 series, compare to Holmes total air hepa type filter-HAPF30AT.Helps capture 99.97% allergens and pollutants from the air, Perfect for reducing odors from pets, tobacco smoke, cooking fumes and other unpleasant household odors.Compatible with aer1 ready air purifiers.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 filterPremium Carbon Filter absorbs and eliminates odors that come from pets, nurseries, kitchen, garbage, or litter boxes.Color: blue + white/ blackProduct Size: 10 x 4.6 x 1.2 inchMaterial: Composite material/spongePackage Contents:3 x filter4 x carbon spray spongeOnly 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.