16 1/4x21 1/2x1 Aerostar Air Filter

The 16 1/4 x 21 1/2 x 1 Aerostar is sized for a nominal opening that's one of the harder filter dimensions to source through retail channels. Actual size is 16 1/2" x 21 1/2" x 3/4". Custom and semi-custom HVAC installations often spec dimensions like this where the return opening doesn't match a standard nominal size. Three MERV grades cover the residential range. MERV 8 for baseline dust, lint, and pollen filtration. MERV 11 for pet households and mild allergy concerns. MERV 13 for fine particulate capture - smoke, bacteria, virus carriers, wildfire particulate. Pleated synthetic media construction with an electrostatic charge handles the filtration work. The pleats provide substantially more surface area than a flat fiberglass filter would offer at the same nominal size, which is what gets you the 60-to-90-day service interval in typical residential conditions. The electrostatic charge improves capture of sub-micron particles where mechanical filtration alone reaches its physical limits. Manufactured by Con-Air Industries in Orlando, Florida. Cardboard frame, reinforced to hold shape under blower suction. Custom and odd-size returns benefit from precise dimensional matching - a filter even 1/4 inch off-spec leaves a gap where unfiltered air can bypass the media entirely. This filter is sized to fit without modification.