Terratrip 303 Geotrip Tripmeter, launched in 2013. The 303 GeoTrip with GPS tracks upto 48 satellites simultaneously, this can give extremely high accuracy typically 0.2% of distance driven. The GeoTrip GPS is far more accurate than the GPS inside a smartphone or most car Sat Nav devices. Installation is simple with our bracket, either suction to the windscreen or bolt to the vehicle, then connect to the cars 12 volt supply. No more installation is required, but if you require a mechanical probe,you can also connect 1 or 2 in addition. If you connect a probe, then you have the added feature of probe fallback - if GPS signal is lost due to a tunnel or similar, then the probe will automatically take over. If no mechanical probe and GPS signal is lost, then the unit will estimate the distance travelled when signal is re-gained.