Larry,
Snap-on likes to take credit for the concept, but I remember seeing a German unit at a local dealership about 25 years ago that operated the same way. I was awe struck at the time. Interestingly I was talking to a seasoned mechanic yesterday, and he said he can match any high speed balancer in a closed room with no drafts and a bubble balancer. I believe him and wouldn't put any of my money up to challenge him.
