3M Filtrete Allergen Reduction Plus 2X Dust Filter. This 4-pack of filters is designed with dual-action micro allergen technology to capture small particles and improve air quality. Each filter measures 14 x 24 x 1 and has a 1200D rating for superior performance. The filters are made in Mexico and come in a convenient bundle package. Trust in the reliability of 3M's brand for cleaner, fresher air in your home.