So I returned this product the same day I got it. It was not true to size. I have a large chest but this hung off my shoulders like I was that tan lady from There's Something About Mary.  The only way to tighten it is to put it on, and then have a second set of arms behind you to lace it up and tighten it and pull a bow through.  If you don't have help putting this contraption on, don't bother.
The straps are really flimsy.  I tightened them up, and they barely move at all.  They also got tangled the first try, then by the time I had the thing off the straps were back to their starting point.