I buy these every year. They hold letter size folders or legal size if you turn them the other direction. I stack them 5 boxes high in long term storage and they never collapse.
Works just fine for my needs. Some of the boxes' perforation did not go through all of the way making it somewhat difficult to separate some pieces (just an annoyance). I'd buy these again.
I found these economy priced storage boxes perfect for moving my office stuff. The price was right too. They are as good as the more expensive Bankers Box.