Aerostar 18x20x1 MERV 11 – 4 Count – Pleated HVAC, Furnace & Air Conditioner Filters – Removes Dust, Cold & Flu Germs, Lint, Mold, Pet Dander, Allergy-Causing Pollen, Smog & Smoke

Customers find the air filter to be well-constructed and effective, with good value for money. The functionality receives positive feedback, with one customer noting it works more like an air purifier. Regarding size compatibility, customers have mixed experiences - while some say it fits perfectly, others report it doesn't align properly with their furnace.