Air Filter Box with High Efficacy Filter, 4-Inch

Air handler filter slot difficult to navigate when replacing filter 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 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

return to the feature slot This is just one of many ways to form a return air box or plenum for an electric air handler to