Works fairly well in keeping the sat nav on my dashboard. However, you do need to get the balance right particularly if the sat nav is on a flexibe neck as it can topple over. Once you have found the best position on the mount though it does work well.
This really did slow my greedy labrador down who generally seems to inhale food with no chewing at all. Unfortunately he did actually chew the bowl itself and destroy it but will buy another and give it another go.
I thought this book would be very helpful and is certainly full of information. However my son put his PS together using information from school and his tutor and did not open it! There is a danger in buying too much the first time around but if you want a reference guide to use this does seem a good one.