The TomTom External Antenna for GO 510 and 910 and ONE Navigators ensures you receive optimal GPS reception for your TomTom ONE or TomTom GO 510 or 910 navigators. While many athermic heat-reflecting windshields and built-in windshield heaters block or reduce GPS signal reception inside your car, the waterproof TomTom External Antenna overcomes this to make sure you get the best possible GPS reception. This unit consists of a magnetic GPS antenna with plenty of connecting cable, making it a snap to quickly place inside or outside your car, without requiring any difficult or permanent installation.