Set button M function:1. Short pre: Switch between MPH/H and KM/H (Note: The MPH/H icon lights up to MPH/H mode, and the MPH/H icon goes to KM/H mode)2. Long pre 1S, the slope level resets the balance3. Pre and hold 3S to turn on the sound or mute Product Introduction:1. smart GPS multi-functional horizontal speedometer for driving, fully supports2.High-precision monitoring of car speed, vehicle tilt angle, vehicle pitch angle changes, compa, time and car battery voltage status, to ensure your driving safety. Product Function:1.Precisely shows vehicle tilt angle with clear notification, when the angle is over 40, alarm alerts.2.Precisely show vehicle pitch angle changes,when the angle is over 40the alarm alerts to insure your safety.3.After connected to power supply, there will be backlight inside, which will help you see accurately in case of night or dark situation.4. Elevation error within 5- 100 meters.5. After the vehicle starts the speedometer starts automatically, after car parking the meter will be in sleep mode automatically.6.Over speed alarm.Fatigue driving alarm alerts after driving for 4 hoursNote:1.Largeobstructions such as the underground parking lot, tunnels, high-rise buildings,etc. will interfere the GPS signal searching, which normally lead to failure toread the speed data.2.There is a certain error of altitude data within, a range of 5 to 100 meters in low altitude areas, while the error in high altitude, areas can be ignored. The cause of this error is related to satellite signals.Features:1.Applicable to Asian cars, American cars, European cars.2.Equipped with high-precision satellite GPS signal module.3.Automatically monitor vehicle driving conditions.4.Adjust the brightne of the screen by using the sensitivity of the light sensor.5. Free rotation, which is more sensitive.6.It adopts color HD LCD display with high resolution.Package:1x X901x Battery clamp cable1x User manual Product Instructions:1. Park the car on a level surface, stick the adhesive on the product, adjust and fix it in the vehicle for easy horizontal view.2. Before driving, connect the power supply and wait to receive the satellite GPS signal until the data shows normal.3. Long and hold the setting button and click the start button to adjust the electronic clock.4. Pre and hold the start button, and click the setting button to adjust the time of the X90.