Can some one explain trim rings?

[UpaDowna]

I know what they are and what they do but I am wondering as I build would it be wiser to get a window with a 1/8" ring or 2.25" ring? These are pretty much my only options with the style window I am looking at. This will go in a cargo van with no interior paneling yet. However the intent is to add paneling of some sort which more than likely will be a DIY or a prefab liner made for cargo van shells.

thanks

[JWA]

Might be helpful to see which windows are under consideration.

[UpaDowna]

JWA-

Yeah I am looking at some CRL windows that feature a metal trim ring. Not sure if you're meaning the exact model number or why that would matter, but it is VW60099L. The issue I was having (ordered the windows so it's a done deal) was simply trying to identify which trim ring was optimal for interior builds. I decided with the 2.25 ring so I can frame out a trim piece and not have it disappear when I dial in the interior. Who knows if that was a wise choice or not but it was a decision none the less!

One thing I did discover is that apparently Butyl tape is the way to go to seal windows and not silicone, which was news to me as I thought silicone would have been perfect!