Quest MERV 13 Filter 18" X 20" X 2" for Quest 506 506 277V 746 & 876Description Product Details: Quest MERV 13 Filter 18" X 20" X 2" for Quest 506, 506 277V, 746, and 876 Quest MERV 13 Filter 18" X 20" X 2" for Quest 506, 506 277V, 746, and 876: Superior MERV13 filtration removes more harmful contaminants from the air such as dust, pollen, mold, bacteria, and some viruses to prevent cross contamination and unhealthy conditions. MERV13 filtration is 65% more effective in capturing dangerous particulates from the air