Nominal Size: 18 x 20 x 1, Actual Size: 17 1/2 x 19 1/2 x 3/4 (17.5 x 19.5 x 0.75) Measure your air filter for the exact size and compare it to our actual size to ensure proper fit. Ideal for normal air filtration and will help those with mild allergies. Nordic Pure MERV 10 is equivalent to MPR 1000 Made in the USA Nordic Pure MERV 10 Pleated AC Furnace Air Filters provides filtration for both home and commercial environments. Our MERV 10 furnace filters are comparable to HVAC filters with the rating of MPR (contact info removed). Nordic Pure furnace air filters are manufactured using a heavy duty, moisture resistant beverage board frame and the media is electrostatically charged to attract unwanted particles. The media used will not promote the growth of bacteria or mold on the air filter and is better at trapping airborne particles than fiberglass filters. For fresh, clean air in your home and office, it is important to regularly change your AC filter to improve indoor air quality and help your HVAC unit perform more efficiently. We recommend changing your filter every 1-3 months, depending on your environment. People with pets or those who suffer from allergies should change their A/C air filters more often. Important Note: Almost all air condition filters have a different Actual Size (the exact dimensions) than Nominal Size (the name) printed on the air conditioning filter. It is best to measure the exact size of your A/C filter and compare it to our Actual Size to be sure your HVAC replacement filter fits.