How would you go about adding a filter slot to this? : rhvacadvice

How would you go about adding a filter slot to this? : rhvacadvice return air support box with filter slot 74846 Southwark FB Furnace Support Box with Filter Slot, 20 x 25 x 1 Inch, 21 Inch W x 18 -12 Inch H Ready To Ship! 17 In Stock Now! Check return of the green knight slot Install the filter media box between the return air plenum and the air handler box 2 Slide the filter into the slot and place the filter

return of the green knight slot For additional dust prevention, there is also a dual electro-conductive and fluorine coating on the optical filter covering the sensor Kensington security slot

return air box with filter slot Install the filter media box between the return air plenum and the air handler box 2 Slide the filter into the slot and place the filter slot, these are not provided with this product For an option with removable channels for multiple filter sizes, see our FRB filter rack base; Come in a