Does what it's supposed to

I have owned this for about 1 week now after buying it for $40 after getting a speeding ticket. I have driven down I5 for about 1000 miles and it has warned me on MOST occasions when a patrol car has been near.
There were a couple of instances where it did not trigger whatsoever, both times were when the cop was stopped and was writing someone a ticket. I guess they must have had their radar turned off at the time.
I plan to take the car in known areas where police station themselves to catch speeders to verify its effectiveness. So far however it has done what it is supposed to.
Comes with relevant fixtures to mount to dash or windscreen.
Good value
Sturdy construction
Audible and visual warnings are clear