FILTRATION: With high filtration efficiency, the MERV 13 Pleated HVAC Furnace air filter effectively captures up to 90% of airborne particles from .3-10 microns particulates to help improve the overall air quality in your home. EASY TO READ AND USE LABEL: With a location on the label to let you easily mark the date you have installed the filler, helping you to know when it is time to replace the air filter. Locate the air flow direction to quickly install the filter into your HVAC system REPLACEMENT TIME: For optimal performance, replace the HVAC filters every 90 days, or sooner if the filter becomes dirty or damaged DIMENSIONS: The HVAC air filter's nominal dimensions are: 20 x 20 x 1 in. Actual filter dimensions: 19.5 x 19.5 x .75 in. CONTENTS: Included in the package are four (4) MERV 13 HVAC filters., Weight: 0.46 Pounds, Manufacturer: Filter Monster