The 25x30x1 Aerostar measures 25" x 30" x 1" actual, sized for a nominal 25x30x1 return on larger residential systems. Returns in this size appear on furnaces serving 3,000-plus square foot homes and on some compact light commercial units. MERV 8 covers baseline residential filtration. MERV 11 handles pet households and most common allergens. MERV 13 captures fine particulates including bacteria, virus carriers, and wildfire smoke - the grade for households with respiratory health issues. Pleated synthetic media with an electrostatic charge built into the fibers handles the actual filtration. The pleats give you substantially more surface area than a flat fiberglass filter would offer at the same nominal size, which extends the service life to 60 to 90 days under typical residential conditions. The electrostatic charge catches sub-micron particles where mechanical filtration alone reaches its physical limits. Manufactured by Con-Air Industries in Orlando, Florida. Cardboard frame, reinforced to maintain shape under blower suction. Larger residential systems run their blowers longer than smaller systems on a per-day basis, which means the filter loads up faster on a calendar basis - plan on the shorter end of the 60-to-90-day range for MERV 8 and 11, and closer to 30 days for MERV 13.
