by 4" Actual Glasfloss. Inch Filters MERV 3-3/4 Air x 19-1/2 Size: 20x20x4 of Pleated x 6 10 19-1/2 Pack

6 Pack of 20x20x4 MERV 10 Pleated 4" Inch Air Filters by Glasfloss.   Actual Size: 19-1/2 x 19-1/2 x 3-3/4  Filtration Rating: MERV 10. Comparable to 3M/Filtrete MPR rating 600 to 800, or FPR rating 5 to 6.  Protects from Lint, Dust, Pet Dander, Pollen, Dust Mites, Smog, & Mold  Note: Does not replace 5" inch or 4-3/8" Depth filters. Please check actual filter size needed. Made in the USA