The Plantronics USB adapter slots into the 12V DC socket of your car and provides a full 1000mA of power for any USB device.
This is intended for use with the Plantronics range of Bluetooth devices, but will serve to provide charging and/or power to any USB device with an input of 1 amp or less.
There are many cheaper USB adapters on the market, made from inferior products. This is a top-quality product from a well-respected manufacturer and comes with free shipping and a 12 month money-back guarantee.