Good reminder, but doesn't stop you slouching
I ordered the medium, since I fit in the size indicated, but it's a bit small, so you'd expect that it would do a good job of support.  However, the back piece is flexible foam, and while I'm aware of it being there it does nothing to stop me from slouching.  I was hoping for more support, so that if I started to slouch I wouldn't be able to, and would correct my posture.<br />It's not uncomfortable, and if you're paying attention it will help you sit straighter, but it's just ok.  I think the large might have been a better fit, as the shoulder straps are tight even when extended to their fullest length.  I'm average size, 5'7", so if you're about my size you may want to wait for the large!
Rating: 3 stars