The 18x18x2 Aerostar measures 17 1/2" x 17 1/2" x 1 3/4" actual, sized for a nominal 18x18x2 slot. A 2-inch filter in this nominal size holds substantially more debris than a 1-inch equivalent and runs at lower pressure drop, which extends both service life and blower lifespan. MERV 8 handles standard residential filtration. MERV 11 covers pet households and mild allergy concerns. MERV 13 captures fine particulates including smoke, bacteria, and virus-sized aerosols. The deeper pleat depth makes higher MERV grades more practical: pressure drop falls as filter depth increases, so MERV 13 in a 2-inch is significantly easier on the system than MERV 13 in a 1-inch. Pleated synthetic electrostatic media handles the filtration. Cardboard frame, reinforced for shape retention under suction. Manufactured by Con-Air Industries in Orlando, Florida. Expect a 4-to-6-month service life on MERV 8 and 11 in typical residential conditions, 2 to 4 months on MERV 13 under similar load. Heavy-load conditions - multiple pets, active cooking, smoke events - shorten those intervals regardless of grade. If you're moving from a 1-inch fiberglass to this 2-inch pleated unit, expect a noticeable improvement in both filtration performance and the time between changes.