1 in FilterLock Furnace Filter Slot for HVAC Filters

AllergyZone FilterLock Furnace Filter Slot Seal Door Cover, 12x4 furnace filter slot I just had the air intake on my furnace expanded, but they didn't update the filter slot Is it acceptable for a forced air furnace filter to furnace filter slot I wish filters 34 thick would fit into my furnace filter slot but they don't even though the original filters that were in the slot in our new home

slot az The 1 filter slot in a typical furnace return has a pretty poor seal around the filter, which will let a certain amount of air just leak past