22x26x1 (Actual Size) Accumulair Diamond 1-Inch Filter (MERV 13) (4 Pack) 22x26x1 (Actual Size) Accumulair Diamond 1-Inch Filter (MERV 13) (4 Pack) MERV 13 Rating Each filter lasts up to 3 months. Supercharged pleated panel filtering media ideally suited for capturing fine airborne allergens such Buy a year of filters in one purchase ( Each filter lasts 3 months under normal use)