I have the 7710 model. When I got it out this spring, the 12 v charger had broken. McNally sent me a new one free. Good for them. On the current trip it sent us to the wrong street once and later wanted us to backtrack several miles when we were less than 2 miles from our destination. Overall, we are not all that pleased. I guess it keeps us out of places not fit for an RV but it seems to take the long way around sometimes. Also, the canned voice does not pronounce some words clearly