Purolator Hi-E 40 Extended Surface Pleated Air Filter, Mechanical MERV 8, 16" W x 20" H x 1" D, 1 each. The Hi-E 40, supplied by Sterling Seal & Supply is a medium efficiency pleated filter, available in 1", 2" or 4" depths and several standard face sizes to accommodate most system requirements. The 100% hydrophobic synthetic media provides 35-40% average efficiency and nearly 95% average arrestance. The Hi-E 40 is effective as a stand-alone filter or prefilter. Support grid made of Galvanized Steel, PVA adhesive not affected by mold or Microbial Growth; Moisture resistant. *** FACTS ABOUT HOME AND BUSINESS AIR FILTERS, ALLERGIES, AND FILTER QUALITY *** When looking to replace your air filter, there are typically two different sizes you need to understand, "Actual Size and Nominal Size". First: The Actual Size consists of the true dimensions of your filter when measuring length, width and Depth (thickness). These dimensions typically include a fraction of an inch within them. For example: 19 1/2 x 19 1/2 x 3/4 Second: What you might not realize is that filters are not sold by their actual dimensions. Instead a rounded up number is used to label filter packages. This measurement is referred to as the "Nominal Size". Third: So a filter with actual dimensions of "19 1/2 x 19 1/2 x 3/4" will have a nominal size of "20 x 20 x 1", and that will be the measurement to look for when buying your replacement filters. *** Check your air filters every month *** Heating and cooling can account for more than 50% of your home energy use. By cleaning or replacing air filters regularly, you can improve the performance of your system and reduce energy costs. Save up to $75 per year!!! A dirty air filter reduces the air quality in your home. Poor home air quality can aggravate allergies and asthma, particularly childrens allergies. Change your filter for your familys health. ... A dirty air filter makes your heating and air-conditioning systems and your ducts get dirty faster. FI-2401-SP1x1