Nominal Filter Size 20 x 25 x 5 Actual Filter Size 19.75" x 24.25" x 4.875" Merv 8 Performance Made in the USA 100% Performance and Price Guarantee The Glasfloss Z-Line 500 AB (Air Bear) & 300 AB (Air Cub) are an ideal replacement option for the Trion Air Bear and Air Cub filters. The ZLine 500 AB & 300 AB incorporates 100% synthetic fibers that are thermally-bonded, and manufactured in an engineered gradient structure. The Z-Line 500 AB & 300 AB achieve a MERV 8 rating when tested in accordance with the ANSI/ASHRAE 52.2 Test Standard. Pre-applied gaskets on the assembled filters helps prevent air bypass. Each filter is sealed in plastic to avoid contamination before use. Glasfloss Z-Line Series Air Cleaner Replacement Filters utilize 100% synthetic media that is laminated to a galvanized steel backing which stabilizes the media during operation. The pleats are formed in a radial configuration and controlled with separators on the air-entry side to ensure proper dust-loading. The pleated cartridge is encapsulated and bonded into a heavy-duty beverage-board frame to ensure filter integrity in high-moisture applications.