When open it is not rigid. Somewhat flexible. However I loaded it with 50 - 60 pounds of outgoing mail and carted it to the USPS. Rolls nicely. I paid about $30 and feel it was worth every cent. The previous one was rigid and lasted 20 years. I'd suggest when not in use it be stored in a clear plastic bag like from the cleaners. Because it is black it will show dust & dirt. It really looks great brand new! The handle seems more sturdy than on our expensive luggage. First time out it was terrific!
The ad states good up to 70 pounds. Only 45 pounds had the sides bowed on the bottom. Not certain I'd want to put 65 or 70 pounds in it. Otherwise it works as advertised. Pulls smoothly and handle goes down easily for storage.
For the first time ever in shopping at Staples delivery was horrible. I've had one of these boxes for the last 15 years and it was great but finally broke. This one is not of the same quality plastic. It's thinner. I hope it holds up.