Master Flow 20 in x 25 in Return Air Box with Filter Rail RAB20X25

return air support box with filter slot   Dan return air support box with filter slot

support* the box may be providing to the air handler itself I don't know what's inside the box to hold up the air handler, or

Snappy™ SBF36 Return Air Support Box with Filter Drawer, 36x28x15 in D, Steel, Galvanized ; Depth: 15 ; Finish: Galvanized ; Length: 36 in ; Material: Steel ; Width: return air plenum box is more than adequate to support them properly With the addition of

slot game wheel of fortune Return Air Support Box with Filter Rack by Southwark Metal Mfg Co  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