The frames actually have a black plastic frame around them, about 5/8" on the sides and less than 1/8" around the front; the picture didn't show this and I almost didn't buy them, because in the picture they just look like pieces of glass or plastic. I've added a (not very good) photo to show the frame.
I'm just in awe of whoever designed these, they're so clever. It took me a time or two to really get the hang of popping the glass out and putting it back in, and inserting the little stand on the back; now they're easy to use and I'm going to buy more.
As others have noted, they aren't quite 5" x 7", they're more like 4-15/16" x 6-15/16", which is OK for me because I have a good paper cutter and I just trim my photos.