The Filtrete Ultra Allergen 25x25x1 air filter carries a Filtrete MPR (Microparticle Performance Rating) of 1500, which is equivalent to approximately MERV 12. This rating allows the filter to capture microscopic particles such as pet dander, smoke, smog, mold spores, pollen, dust, and dust mite debris, making it ideal for households with allergy sufferers. The pleated electrostatic design uses 3M's exclusive Filtrete technology to attract and trap airborne particles as small as 1 micron.

3M recommends replacing the Filtrete Ultra Allergen 25x25x1 filter every 3 months for optimal performance in standard residential HVAC systems. However, homes with pets, smokers, or high dust levels may need replacement every 60 days. Marking the installation date directly on the filter frame (using the provided date boxes) helps track replacement timing and ensures consistent indoor air quality.

The nominal size is 25x25x1 inches, while the actual measured dimensions are 24.69 x 24.69 x 0.81 inches. Always verify your HVAC system accepts this exact nominal size before installation. The filter features an arrow printed on the frame indicating proper airflow direction, which must point toward the furnace or blower unit for the electrostatic pleats to function correctly.

With its 1500 MPR rating, this filter captures large particles like lint, dust, and pollen, plus microscopic allergens including pet dander, mold spores, smoke, smog, bacteria, and virus-carrying particles. The 3-in-1 technology uses exclusive electrostatically charged fibers that attract and trap both large and small particles while allowing cleaner air to flow through your HVAC system. It is not, however, designed to trap odors or gases—for that, consider the Filtrete Odor Reduction series.

The Filtrete Ultra 1500 MPR is compatible with most residential central heating and air conditioning systems that accept a 1-inch thick 25x25 filter. Due to its higher MPR rating and denser pleated media, ensure your system's blower can handle the slight increase in static pressure. It is not recommended for systems requiring thicker filters (2", 4", or 5") or for window AC units. Always confirm your return air grille or blower compartment accepts the 25x25x1 nominal size before purchase.