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.
At the first i found box a bit hard to assemble. Afterwards it became second nature. I got a 10 pack just in time to not only store some hanging file folders ( I like the shape for both letter and legal sizes) but also to store and stow Christmas lights and ornaments out of sight and out of mind till 2021. They are more than adequate. and strong. Some plastic file boxes i bought several years ago at much higher price have deteriorated and cracked apart.