The FME 40 is a medium efficiency, self-supported extended surface, pleated filter to accommodate most system requirements. The lofted, non-woven media composed of non-dyed natural cotton and synthetic fibers provides 25-30% average efficiency and 90-93% average arrestance. The FME 40 is effective as a stand-alone filter or prefilter. UL Class 2. Cases of 6 Pleated 16" x 20" x 4" Disposable Furnace or Air Conditioner Filters $80.00, 2/$144.00 Cases of 6 Pleated 20" x 20" x 4" Disposable Furnace or Air Conditioner Filters $88.00, 2/$158.40 Cases of 12 Pleated 12" x 24" x 4" Disposable Furnace or Air Conditioner Filter $152.00, 2/$273.60 Cases of 6 Pleated 18" x 24" x 4" Disposable Furnace or Air Conditioner Filter $93.00, 2/$167.40 Cases of 6 Pleated 24" x 24" x 4" Disposable Furnace or Air Conditioner Filters $106.00, 2/$190.80 Cases of 6 Pleated 16" x 25" x 4" Disposable Furnace or Air Conditioner Filters $87.00, 2/$156.60 Cases of 6 Pleated 20" x 25" x 4" Disposable Furnace or Air Conditioner Filters $99.00, 2/$178.20 Schill's, llc 103 Curtis Street Arlington, WI 53911 Limited Hours Customer Service: 888-528-0225 Email: Info@Schills-Humidifier.com Fax: 608-592-3205 Manufacturer's Numbers: Aprilaire: 800-334-6011 Broan Fan/Heater Questions: 800-637-1453 Delta Faucet Questions: 800-345-3358 Grohe Faucet Questions: 630-582-7711 Hart & Cooley Questions: 616-656-8200 Kohler Faucet Questions: 800-456-4537 Moen Faucet Questions: 800-289-6636 Stiebel-Eltron: 800-582-8423