System:  -OBD System (For OBD2 car).  Functions:Vehicle speed,engine RPM,fuel consumption,water temperature,voltage,clock,mileage,travel time,travel distance,altitude,number of compass satellites, RPM icon.  -GPS System  (For all car).  Functions:Vehicle speed,time,voltage,travel time,travel distance,travel direction,altitude,satellites number,speed Icon.  When the OBD system is not compatible,please switch to the GPS system and plug with the USB cable.     Feature:  1.Compass: Show the driving direction when the vehicle speed >5KM / H, Display navigation information when using navigation.  (W=West, NW=Northwest,N=North,NE=Northeast,E=East,SE=Southeast, S=South,SW=Southwest).  2.Light sensor: HUD can automatically adjust the brightness according to the environment.  3.Lane display: With the navigation function of the mobile phone APP, display the lane where the vehicle is driving (the overseas version does not support this function).  4. Fault code icon,Phone connection icon,OBD system,GPS system (GPS icon will flashing  until satellite signal been founded) 5.Camera monitoring area (overseas version does not support this function).  6.Multi-function area: RPM,water temperature,voltage,fuel consumption,altitude,mileage,navigation distance point,driving time,power test,satellites number,clock.  7.RPM=rotating speed,°C/F=water temperature,V=voltage,LHK=fuel consumption,ASL=altitude,TRIP=travel mileage, D=navigation distance point,MIN=travel time,a + =100km acceleration test,GPS=satellites number(GPS system can be used after 5 satellites are found) 8.Vehicle speed display.  9.Speed unit: MPH=Mile/hour, KM/H=kilometer/hour.  10.RPM icon.  Specification:   Working Voltage: OBDII 12V.   Standby current: <25mA.  Operating temperature: -25℃—85℃ .  Size: 14.3x7.4x6cm.     Package Included:  1X  HUD Display;  1X  OBD Cable;  1X  Lighter Cord;  1X  Cleaning cloth;  1X  Manual