useful for letter or legal files. also turns out to be a good fit for a lot of other things so makes a good general purpose storage container. very modest unit cost so good for applications requiring a lot boxes that have to stack neatly. perforations are not alway cut clean through and does not accommodate hanging folders well.
I use these for personal storage. Durability is fine but when assembling the boxes the perforations to tear where needed were not deep enough so the corrugation seperated in various spots....a little "chinchy". I would recommend but with "warning".
These are just a good size for packing as anything larger is hard to handle. The only issue I ran into was with a few boxes that didn't have good perforations and had to be cut through in order to assemble. Have used these for storage of "office" things too. They are really tough and because of handles easy to move.