I have this on my H2 for 4 months now. I highly recommend it. As one guy mentioned, it is idiot proof. At 7 feet - slow beeps - green light, at 5 feet - faster beeps - yellow light, at 3 feet - constant beep - red light. It's funny how one mentioned "curb". IMHO, the curb is the last of your worries. I have tested this with small kids (with engine off ofcourse). It was always on the money distance-wise whether directly behind or to the side. Oh and on those dark, foggy and/or rainy nights, this thing works just the same. It uses sonar waves like the military uses. And you can transfer to any vehicle (provided it has a hitch) in no time. I don't know about the H3, but I only use my H2 on weekends and this thing is plugged in full time and does not drain my battery.
Here's the thread on the H2 side:
http://www.elcovaforums.com/forums/s...=sensor+backup
Product website:
http://www.sonarstep.com/
I forgot to mention it won awards from Popular Mechanics - Editor's Choice Award and SEMA Int'l Product Award.