My Beltronics can pick up a cop with radar on about a good 30 seconds before I see the cop, over the hills and around the corner and 360 deg if he is behind.
But I travel back roads mostly and I noticed that most highways in MA have the instant on where the radar goes off if the cop has his hand held unit pointing directly at you so traveling in packs works good as well because he will not pull over a number of cars traveling at the same speed
