Ok so I didn't exactly roll it I-71 North bound I got a single audible alert that went to a "J" and the Dee Da doo or whatever sound. It went to the J so quick I couldn't see what bad it originally picked up. The "J" means junk and is usually a Cobra RD correct? If this is what the device does when it finds a Junk signal then I'd have to say it works great. Just after the J alert a Porsche flew by with a RD.