As others here have stated, it's a great tool that you have to learn to use. I've been using my V1 for years and wouldn't go on a road trip without it. While it's not magic, it will keep you from getting a stupid ticket. Especially in a little towns where the speed limit drops quickly from 50 to 30mph. In addition to avoiding a ticket, it also let's you prepare for the panic breaking by the cars in front of you that see the speed trap at the last moment.