Holmes Replacement Modular HEPA&trade; Filter Effectively absorbs airborne bacteria, pollen, mold and spores, cooking odors, tobacco smoke and particles, pet dander and hair, dirt and dust, and many other household odors for many Holmes and Bionaire room air purification systems that use HEPA technololgy. For use with Holmes air cleaners - HAP240, HAP2400, HAP2404, HAP242, HAP243, HAP244, HAP246, HAP260, HAP412, HAP422, HAP424, HAP440, HE300-IQ For use with Bionaire air cleaners - BAP1242, BAP1412, BAP1422, BAP1552, BAP1825. BAP242, BAP260, BAP422, BAP815, BAP825 Change your filter every 4 to 12 months depending on the air quality in your home or office Package of two filters