Tier1 Replacement for 3M 12x21x1 FAPF03 Ultra Clean Air Purifier Filter 6 Pack Fits the 3M Filtrete Ultra Clean Air Purifier FAP03-RS Cost-effective alternative to the expensive OEM filter Actual Size: 11-5/8 inches (width) x 21-1/8 inches (height) x 3/4 inches (thickness) Merv 8 Replacement for the 3M Filtrete FAPF03 & FAPF03-6 Air Purifier Filters