External magnetic GPS antenna with 3M-MCX connector to suit Racelogic PerformanceBox, DriftBox and VBOX Sport.Some modern cars are fitted with a special windscreen that cuts down the amount of UV (Ultra Violet) rays that will be transferred through the windscreen which help cut down on glare. These windscreens are called Athermic, or UV Coated and will dampen/reduce GPS signals coming through the windscreen.If your car does have this type of windscreen you will need to use this external GPS antenna that magnetically fixes to the roof of your car.