20X23X4.25 MERV 13 BDP Replacement Filter

BDP FILCCFNC0024 and FILBBFNC0024Nominal size 20" x 23" x 4 1/4" (Actual size 19 7/8" x 22 5/8" x 4 1/4")Removes atmospheric and household dust, coal and insecticide dust, mites, pollen, tobacco smoke, cooking smoke, grease, mold, fungi and more down to 0.3 micron.This product is listed and rated by Underwriters Laboratories as U.L. Class 2.What is MERV