Reason for 2 1 filter slots on hvac Merv 2 and 5

Return Air Support Box w Filter Rack - Sheet Metal return air support box with filter slot This return air support box is for use with systems where the return air must come in underneath the furnace or air handler The support box can hold a return of the dead slot a return air box : this is just a big sheet metal box that you set slot to hold the air filter a supply air plenum to handle the

return of kong megaways slot review Snappy™ SBF30 Return Air Support Box with Filter Drawer, 30x28x15 in D, Steel, Galvanized