Park the car on a level surface, stick the adhesive on the product, adjust and fix it in the vehicle for easy horizontal . driving, connect the power supply and wait to receive the satellite GPS signal until the data shows normal. Long and hold the setting button and click the button to adjust the electronic clock. Press and hold the button, and click the setting button to adjust the time of the X90. Precisely shows vehicle tilt angle with clear notification, when the angle is over 40, alarm alerts. Precisely show vehicle pitch angle changes,when the angle is over 40the alarm alerts to insure your safety. After connected to power supply, there will be backlight inside, which will help you see accurately in case of night or dark situation. Elevation error within 5- 100 . After the vehicle starts the speedometer starts automatically, after car parking the meter will be in sleep mode automatically. Over speed alarm. Fatigue driving alarm alerts after driving for 4 hours Power: DC 10V~30V Depression&Elevation angle: -40 +40 Clock Error Value: Less than 1 Voltage measurement accuracy: 0.5V GPS Cold Time: 32s (average) GPS Data Refresh Time: 1s Working Temperature: -40 ~ +80 Roll Angle:-40 +40 Voltage Measurement Range: DC5V~30V Speed Accuracy: Less than 0.36Km/h GPS Hot Time: 1s (average) Wireless Transmission Frequency:2.4GHz Product Size:170x68x60(mm) Colour:black Material:Plastic + Polycarbonate Package Contents: 1 x Head-up display 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.