Why are there two air filter slots in my HVAC system?

filter slot I contacted the company and they said “you just have to It had to cover the entire media and be strong enough to hold the filter

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furnace filter slot filter slot to simply slide the filter inout The resistance is HVAC tape Nothing felt any different in terms of stability of the

journey to the wealth slot png I have a house where the furnace has a 25 x 1 wide slot in the air intake where I slide the 16x25x1 filter in from the top