I would suggest find out from a radar forum which will give you people who are into the hobby with lots of experience as most of us are amatures at it.
They do work though by sending multiple scrambled data to the gun so it reads an error ,most officers know this and will reaim at you and shoot ,hopefully you early warning system has alerted you and you slowed down in time. They can only work for a few seconds and get very hot. Usually placed above your front plate.