Flanders FilterLock Air Filter Accessories - Magnetic 2-Piece Design

Furnace AC Air Filter Door DIY metal furnace filter slot cover Comments142 ; How To Upgrade Your HVAC Air Filter To A 5” Honeywell -6 Month Or More metal furnace filter slot cover I think I'll make a similar cover for my furnace filter slot I see the potential for better return air flow upstairs by restricting leakage

metalen kast met slot metal duct work; Installs in FilterLock satisfies the department of energy recommendation that the furnace filter slot be covered to avoid air leaks