The problem with those.. and radar detectors... is that they don't prevent the cop from eyeballing how fast you're going. And, guess what... on a highway with even a few cars on it... if you're going significantly faster than the rest of the cars, the cop is gonna see you and know where to aim that radar/laser.
It's just not worth it. I speed a little... like 5-10mph over the limit... but I'm not stupid about it. If I'm in an area I'm not familiar with, I always slow down to the speed limit.
All it takes is a little common sense and some attention to the road and your surroundings... and you shouldn't need a radar detector, not to mention a scrambler. Save the money for new brakes and tires... things you'll go through quicker if you speed a lot.