Just so you all know I can catagorically say that you do NOT need to put your laser detectors in the clear square at the bottom centre of your windscreen.
I have mine just above my rear view mirror at the top of my screen and it works fine. i was coming into a village on Saturday, someone flashed me coming the other way so I slowed right down to 30 and about 10 secs later the laser alert went off. Sure enough about quarter of a mile up the road was a chap in a yellow jacket with a laser gun in his hands. He saw my detector in the window and gave me a knowing nod as I drove by