As strong as you'd expect the economy box to be. Easy to assemble. Flaw: top is way too hard to separate from the rest. Tears every time. Needs better perforation.
The boxes are easy to use and store for reuse. They are strong and durable through moving and / or storing books papers dishes....... you name it! I was glad to find the box sets on clearance and hope that Saples continues to carry them. There are directions on how to fold the boxes right on the outside of them. The directions are very easy to read and understand. Thank you to whoever made sure the directions were clearly written with a diagram and big enough to read without having to pull out the reading glasses!