Usage Tips:C90 Head-up Display Elevation Meter Gps Speed Meter Car Accessories f54 1.Head-up display the driving speed. 2.Driving time and mileage calculation and display. 3.Over-speed alarm setting. 4.Fatigue?driving alarm. 5.Altitude display. 6.Local time display with auto timezone adjustment. 7.Easy Setup--Plug & Play- Power through vehicle lighter. No professional installation is required. 8.Compatible with all Cars & Trucks. Use GPS signal guided calculation. No wiring needed to the VSS (vehicle speed signal). 9.Display or KM/h. 10.Auto adjust brightness through sensor for Day & Night driving. 11.Green color data display, your eye. 12.Total mileage display after car stops. parameters: 1.GPS positioning time: 1 to 5 minutes in the open air (The weather will affect the positioning time). There is no GPS signals indoors. 2.Speed deviation: Since the speed data comes from the GPS satellite, slight deviation is unavoidable. 3.Input voltage: DC 5V Input current: DC 50-120mA Working temperature: -30 to 70 degree 4.Driving data deviation is around 2% 5.All driving data will be cleared when power off except the total mileage. Colour:black Material:plastic Package Contents: 1 x HUD Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.