Feature 1. Via satellite positioning, the Inclinometer both can display the vehicle speed with an over-speed alarm and also display the local time. 2.Over speed alarm:Fatigue driving alarm alerts after driving for 4 hours. 3.Can avoid safety hazards caused by too high or too low voltage prolonging the lifespan of the battery. 4. Backlight design: After connected to power supply, there will be backlight inside, which will help you see accurately in case of night or dark situation. 5. Has a buit-in high-precision satellite positioning chip, it is perfectly suitble for self-driving and 0ff-road activities. 6. Elevation error within 5- 100 meters.After the vehicle starts the speedometer starts automatically, after car parking the meter will be in sleep mode automatically. Specification: -Power: DC 10V~30V-Depression&Elevation angle: -40 +40-Clock Error Value: < 1 minute-Voltage measurement accuracy: O.5V-GPS Cold Boot Time: 32s (average)-GPS Data Refresh Time: 1s-Working Temperature: -40 ~ +80-Roll Angle:-40 +40-Voltage Measurement Range: DC5V~30V-Speed Accuracy: < 0.36Km/h-GPS Hot Boot Time: 1s (average)-Wireless Transmission Frequency:2.4GHz-Product Size:170*68*60(mm) Package Included: 1x HUD1x ACC Cable1x Cigare lighter1x Fixed pad1x Instruction manual Return Policy All of our items come with a 30-day free return policy. If you need to return, please contact us, let us know the detailed problem and send us some pictures for confirmation. We reserve the right to refuse any returns for objective reasons. Shipping Policy All of our items are shipped free with tracking numbers. Orders will be shipped within 3 working days upon receipt of payment. Most orders will be shipped within 1 working day. In most cases, shipping takes 8-12 working days.