18" x 20" x 1" ,Up to 15 times more effective than spun glass on sub micron sized particles ,About twice the surface area of flat panel filters ,Designed to provide allergy relief ,Merv 8 low airflow resistance for better equipment operation and to help save energy ,Lasts up to 90 days ,Captures particles as small as 5 microns in diameter- pet dander mold spores ragweed pollen dust mites and debris