Enviroflow 20x25x1 (19.75 x 24.75) Pollen and Dust Control (4 Pack) Nominal Size 20 x 25 x 1. Actual Size 19.75 x 24.75 x 0.75 MERV 8 Rated. Electrostatic pleated media, which performs better than regular fiberglass fibers. Traps dust and allergens such as pollen, mold, pet dander, and dust mites. Each filter lasts up to 90 days Pack of 4 Filters