It picked up real radar, and it also picked up the usual civilian noise. What the 390 does, it does at a budget-appropriate level. A radar detector lives a fairly gentle life stuck to a windshield, and the 390 is a compact plastic-bodied piece weighing just 4.8 oz. In most U.S. states, using a radar detector in a private passenger vehicle is legal. Is there a radar detector app that works as well as a dedicated unit?