24x24x4 MERV 8 AC Furnace 4" Inch Air Filters. Box of 4 24x24x4 AC Furnace 4" Inch Air Filters MERV 8. Qty 4 Extremely low pressure drop and high dust holding capacity Actual Size: 23-3/8 x 23-3/8 x 3-3/4. Engineered and designed for high strength and rigidity Made in the USA