The voltage converter in the car fits perfectly in the cup holder. Because the cable for the 12V on the same side as the outlet is shaking anything, the device can be easily jammed. I use the voltage converter for charging my netbook. Testhalber I took a light bulb (25W) in continuous operation (approx 1 hour drive). The device is not even warm. In addition, I invite even my smartphone HTC TyTNII or my iPod Classic to the USB port. The 12V plug remains well stuck in the cigarette lighter socket.