I think Kenny says it best about what I think of this :D
For those of you thinking of buying this FOR FITNESS PURPOSES (for other uses, the ball is in your court), my advice is 'Don't waste your $$$$$$$!'. At least I wouldn't. They are a joke, and they are downright lying to you. You might be better off with your pilates class.
My opinion is this, if you want to get ripped, defined or build muscle, lift heavy weights, eat lots of protein and fruits and do sprints (this is my twitter opinion, although I don't have twitter):