Enviroflow 17X22X1 (16.5 x 21.5) Pollen and Dust Control (4 Pack) 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 Nominal Size 17x22x1. Actual Size 16.5 x 21.5 x 0.8