Filtrete 20x25x4(SlimFit), AC Furnace Air Filter, MPR 1550 DP, Healthy Living Ultra Allergen Deep Pleat, 2-Pack, Fits Lennox & Honeywell Devices (exact dimensions 19.5 x 24.5 x 3.75)Actual filter size is: 19. 5 in x 24. 5 in x 3. 75 in This filter is compatible with Carrierand Bryant furnaces calling for a 4" filter The higher the MPR, the more microparticles such as pollen, pet dander, smoke, bacteria and viruses your filter will capture from the air passing through it FOR OPTIMAL PERFORMANCE of your heating & cooling system or HVAC system, change your home air filter at least every 12 months for 4in. and 5in. Filters A dirty