When I looked into these a couple of years ago I was told they were erratic and inaccurate at lower speeds and the whine from them was annoying. I also read that some people had suffered problems with short life and limited guarantees. Another problem was you had to match transmission gears to the unit and accuracy wasn't guaranteed. They were not adjustable. A friend not associated with this forum told me one version now uses gps to make the things more accurate and easier to use, but he said he understood those were prone to lose signal in tunnels, from high buildings, transmission towers, etc so I don't know. The comments about breakage and poor warranties were enough to push me away. Speedhut makes some really good stuff, but this is different from their main line.
