I have one and they work great. Very accurate. It is kind of a waste because you can really only use it on the track. You must be on a level surface, and going through any kind of turns throws it off, unless you are monitoring G's. This would be better if I had some safe "legal" area to use it. Get the original Gtech for $39 off ebay. I have that one too, but for $40 you can go wrong.
