I've never heard of them, but it seems like a great idea. I'd like to have one - at home anyway. I can't see having one at the office. Too odd - would cause too much conversation from everyone who walked past.
What I don't see is one that is a height that we would need. They are a tad too short. My knees would wind up above my hips, and that kinda defeats part of the benefits of the exercise. If anyone sees one with adjustable height that would be great.
DonnaP99