Trick, what that guy told you is
The Laser jammers DO NOT give the cop a pre determined speed reading. With a radar detector the cops have them on and you vehicle has to drive through the radar waves in order for the speed to be reflected on the cops display, this is what radar detectors pick up to alert the drive of the speed trap usually before the car is in range of the radar and the driver has time to slow down. With laser gun it is a very accurate point and click to which car the cop desires and it is only on when the trigger is pulled, therefor there is no early warning for laser speed guns. There are no radar jammers as the would interfer with all sorts of other electronics and are very illegal. I'm not sayinmg no one has one but if they do it is not from US retailer. Laser diffusers or jammers work to deflect the speed laser pointed at you vehile and not let the reading return to the gun. All the cop see on the speed reading is ---, or 000 for no reading. This laser gun will most likely not set off your radar detector and if it does its too late. With the K40 system it blocks the laser and alerts the drive that they have been targeted, plus the whole system is hidden so no one is the wiser!!