

Is this metal grate supposed to be installed on the duct itself (i.e. between the return duct and newly installed drywall), or on the wall?
I recently had a low return, added to the first floor of my home. The tech said that there are prongs on the metal duct that are intended to hold the grate in place. I thought I understood what he meant.
When I described that to my handyman, he seemed to know what I was talking about. However, this part was left undone. I thought it would be a simple matter of screwing it in, but now I’m wondering if I have to figure out how to wedge this grate between the duct and drywall. Any advice is appreciated!