I've tested the device this afternoon and was a tad bit impressed with the quality. It uses FM transmitter to send the signal and the car radio unit catches the signal perfectly. My GO 720 navigation system also has FM transmitting function but the signal is not strong enough so I am not happy with the sound quality due to white noise. It uses 87.5 MHz as default frequency like TomTom but I could not notice any interference or white noise.
In short, this cheap device with led display and a remote control works flawlessly and the remote controller proved itself as a very efficient device. I might use this unit during the long haul driving.
I think the manufacturer should have done upside down the sd card reader so a ugly back panel might not be seen.
