Size: 1" X 20" X 25" Assembled Product Length: 25" Assembled Product Height: 1" Assembled Product Width: 20" . Rated 20 times better on small particles than ordinary 1" filters in independent tests • Patented electrostatically-charged Filtrete fibers attract and hold particles like magnets • Retains more particles with pleated surface area • No monthly washing like less-effective 1" permanent filters • Use in furnace or A/C for full three months of air quality protection under normal conditions • 3M reliability and proven performance in every air filter • MERV 11