Our Tier1 P85S.6421H23F 21-1/2 x 23-3/8 x 4 MERV 8 Air Filters (6-pack) are pleated high-capacity filters constructed using electrostatically charged filter media from Kimberly-Clark - a recognized leader in the filtration industry. This 100% synthetic material offers significantly higher particulate efficiency than typical poly/cotton media pleated filters, and captures the smallest and most troublesome airborne particles and allergens, such as particles that carry viruses and bacteria, pollen, mold spores, fine dust and pet dander. The combination of high efficiency, allergen reduction, and low cost make these the ideal choice for homeowners looking to improve indoor air quality on a budget.

• 30 times more efficient than ordinary fiberglass filters at capturing the smallest, most troublesome particles (3-10 microns in size)
• Doesn't promote the growth of bacteria, mold, mildew, or fungi so they're a great choice for families with small children
• Similar to the 3M Filtrete Dust & Pollen filter
• Rated UL Class 2 by Underwriters Laboratories
• Made in the U.S.A.