u/BurritoNipples

so I renovated the house like 6 months ago. I noticed some of my wafer lights sag a little. when I went go adjust them and tighten them the cut was exposed. meaning it was either to big or just sloppy, so he left them just a little loose so it covered up one of the sides being cut more than the other uneven.

anyways I'm stuck with it. I don't want the attic space getting into my second floor. what's the best way to seal this up from inside, the easiest way.

thanks