Air Filter, Standard Grade, Metal Fiberglass, 30 Days, 17.5x23.5x1-In.

17.5" x 23.5" x 1", One Sided, Metal Fiberglass, Standard Grade Furnace Filter, Merv 3, Filtering Medium Is Continuous Filament Spun Glass, Frame Is Made With 1 Continuous Piece Of Chipboard To Guard Against Corner Separation, For Peak Equipment Protection & Energy Efficiency, These Filters Should Be Changed Monthly In Periods Of High Use.