That's just the poster size that you enter in, right?
https://www.levleframes.com/frames/new?height=12.0&width=12....
I punched in 12"x12" and it's showing me various frame/matte combinations that result in a 12"x12" opening.
Customizing a frame to fit a 12.0" x 12.0" print
13 x 13 x 0.75" Black Maple frame with No mat
and Standard glaze. $43.50
Maybe I just misunderstand how frames are described and sold, but I would fully expect to receive a frame with a 12x12" opening ("to fit a 12.0" x 12.0" print") if I bought that frame, and would feel misled if I ended up with a 13x13" opening. Again, maybe that's just how frames are sold, but if that's the case perhaps the site could explain that better.
The ambiguity is a concern for me. Also, I was a little wrong on the $200 figure earlier. The number is actually $150 for two matted prints of mine that I have sitting at home waiting for me to frame them.