What is HUD: Short Head Up Display. It displays driving data on the front windshield such as speed,RPM,water temperature,voltage single mileage etc. HUD avoids the danger of drivers looking down at the dashboard. It ensures the safety of drivers because of watching the data on the car front window glass, and helps drivers to keep the best state on the way. A variety of operating interface modes and colors can be switched freely, It will bring more fun and Technological sense to you. Compatible Attention: Suitable for vehicles produced after 2008. GPS MODEL Suitable for All Vehicle. Dual System, Change free.OBDll mode is not compatible with hybrid electric vehicle,diesel car, pickup truck, RV, computer modified car,it is recommended to use the GPS mode. NOTE: The data shown in OBD2 mode is the vehicle's engine data. OBD2 mode only displays the battery and voltage when the vehicle's engineis not started. Simple Display:Vehicle Speed Engine RPM, HD Display, practical function, let you drive more comfortable for a long time. (plug and play -- Available for 95% car with an OBD2/ GPS interface) The Nano - Technology - High clearness projector, to eliminate unwanted reflections and can make the display information more sharper. The Automatic and manual brightness adjustment mode, and more easy to control the HUD. Multiple functions: Ambient decorative lighting Engine RPM Fault code alarm Fatigue driving alarm .The Alarm icon Light sensor: HUD can automatically adjust the brightness "according to the environment .Speed unit: KM/H, MPH .Multi-function zone: speed,water temperature,battery voltage,driving distance Water temperature icon ,voltage icon.