Hi,

I want to put a HEPA filter in my A/C Air Return Grille. I check local
big box stores and didn't find anything. Strike-out at local A/C
suppliers such as Michael.

I did a google search "HEPA Air Return Filters" and got essentially
nothing. Some sponsored links were promising, but I wasn't able find
anything there either.

Is this not a commonly available type of filters? Are they not
recommended for some reason? Can someone recommend an (online) place to
purchase them?

Thanks!

Sam