1 filter per pack. Helps remove allergens from the air. Reduces unpleasant odors. Captures fine particulates. Maintains consistently high-performance over time. Filter size: 4-1/2" W x 10" L x 1-1/2" D. Fits Bionaire Model No. BAP242, BAP422, BAP815, and BAP825, Holmes Model No. HAP240, HAP242, HAP243, HAP244, HAP246, HAP2404, HAP260, HAP260B, HAP2604, HAP2604B, HAP412, HAP412G, HAP422B, HAP422G, HAP424-U SKU 650479, HAP440, and HE3001.