Carbon Pleated Air Filter for AC HVAC or Furnace. AF carbon filter, comparable with MPR 300 / 600 (clean living and dust & pollen). Two-piece frames are made of beverage board, which stays strong through humidity and temperatures with wire backed synthetic filtering media for optimal equipment protection and energy efficiency, these filters should be changed 60-90 days in periods of high use. These filters have a MERV 8 rating: Removes dust, pollen, mold, dust mites and lint. Made in the USA.