Sierra Wireless Overdrive Pro 3G/4G Mobile HotSpot Heavy Duty Plug-In Car / Vehicle Charger! An outstanding quality charger at a reasonable price! Official circuitry means accurate and safe. One year warranty is offered by the manufacturer against defects. The first automatic stage of this charger offers fast charging until 95% bettery life. The second automatic stage of this charger is "trickle" charge and fully optimizes your battery to 100%.