Remodeling house for sale, missing grills from light fixtures

The basement has recessed light fixtures, with removable grills than
hook inside the cylinder, but they can't find all the grills**

Do they sell grills that could be mounted on top of the entire fixture
(that is, underneath, since the fixture points down), maybe 6 inches
in diameter?

What would these be called? So I can find some and buy them.

Thanks.


**Removed to replace bulbs but replacing the bulb didn't work and
eventually they lost track of 3 grills.