I have this unit connected to my kenwood KNA G421 sat nav unit, and it has saved me so many times on trips both abroad and at home! It was very easy to connect, as you literally just connect one end of the cable to the radio antenna cable from the car, and then the other into your head unit. I was travelling through Germany, and it alerted me to a huge accident with tailbacks further up the road, and rerouted me around it, and we lost about 30mins compared to waiting in delays for hours! It does it's job very well, and I now couldn't have a sat nav with the traffic alerts function. You can set it to show and alert you to 'high, medium, and low severity' incidents, which is useful, as I do sometimes carry on with the original route if it doesn't seem too serious. I do feel that this should be included with the sat nav units, as they are so expensive, and this should be standard on a high end sat nav not an optional extra. However this is just my opinion, and I like it so much I wasn't too bothered to pay for it!