I have been checking these out recently after being stuck in the middle of the mountains and have just ordered this one which I think is going to be a handy tool to have.
Strangely enough wandering will just bought one recently too.
I shall keep you informed on how I get on with it,but even apart from the jump start facility,the extra power pack will be well handy. The jump start can be done with a reverse polarity ( I think thats what it is ) so one can jump start or boost the engine through the cigarette lighter socket.
Sorry it is in french !!