The inside corners are not easily flexible for adding the diplomas, Also I could not get my diploma to fit, it seems that it is too small. I wanted these to work so I tried a second time when I printed my sons certificate from his teacher and it wouldn't fit and I had to cut it to size. Once it was the right size it was still tough to get into the corners, I had to buy thicker paper and it still was tough to get it to work.
I will say the darker texture is great for painting, my son has used a couple to draw and paint on and the thick texture holds up well to the paint. However, if you want these for diplomas I am sorry to say they did not work for us.