I didn't find any weight specifications on the box, unfortunately. I've used mine several times, and it feels really, really solid. One thing to keep in mind is that you likely won't be balancing 100% of your weight on the toy. If you're sitting on the vibrating parts in the middle, your weight is in the middle, and you're not going to crush through the hard plastic. If you're bracing on the sides of the toy, which I've done, it still feels really solid.
I weigh between 130 and 140 pounds, and I've tried putting as much weight as I can on the ends/handles/braces of the toy. I couldn't really use the toy in that position, trying to balance on the toy itself, but it held up really well. I didn't feel it bend or move at all. I don't have any guesses about the weight limit or how it would perform for other users, but maybe my experience will help you with your decision.