I checked that RB2140 style, it has a nice shape but it seats weird, like th top of frame is tilting down my face. The arms are constructed in an angle & that's the way it's made on every piece I checked.
^^I think the 2140's in the larger "54mm" size. The 54mm has a frame that is a tiny bit thinner (less plastic) which is usually the give away. You can see this on the large photo I posted above of A.D.R. in her 54mm black wayfarers.
edit: go back and look at post #45 in this thread. It shows the difference between the 50 and 54 really well.