16 1/2x21 1/2x1 Aerostar Air Filter

At an actual 16 1/2" x 21 1/2" x 3/4", this Aerostar fits a nominal 16 1/2 x 21 1/2 x 1 return - another odd size that hardware stores don't stock and that's a common reason buyers end up ordering direct. MERV 8 covers standard 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 asthma or chronic respiratory health concerns. Pleated synthetic media with an electrostatic charge handles the actual work. The pleats give you substantially more surface area than a flat fiberglass filter 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 the physical weave alone reaches its filtration limits. Manufactured in the USA by Con-Air Industries, Orlando, Florida. The cardboard frame is reinforced to maintain shape under blower suction. Frame collapse is one of the most common failure modes in cheaper odd-size filters, and a collapsed frame allows unfiltered air to bypass the media entirely - the worst possible outcome in a system where you're trying to filter for health reasons. This filter is dimensionally precise to the OEM specification.