i can vouch that these work ive had one for 6 months, i was doing 79 on the cross town came over the hill and 5 troopers there with radar guns pointed, it was kinda funny, i know they knew i was flying but as i jammed the brakes, all i could hear is the jammer screaming as i passed the troopers, the look on there faces were priceless. They couldnt get a lock on me! They didnt even pull me.. But i must warn you guys when a cop pulls you and if they notice it in the dash they go from being normal jerks to major assholes, saying ah thats why i couldnt clock you.. Guess i got to find another ticket to give you... That being said when they approach you make sure its out of sight lol...