Hi Edwin,
Easiest way is to put a framed print into the shopping cart; it will give you choices about paper, frames, etc. It will tell you the kinds of paper, giving a choice of 7 papers; click on question mark at right for more details. Just delete items from cart when done exploring.
Also, if you click on metal prints, and scroll way down, there is some info about the aluminum and how it's mounted to hang on the wall. I think most of the items have this kind of info if you scroll down on each page.
My husband is a photographer, me a painter, and we've been happy with the quality.
Hope that helps,
Retta