Intelligent Solar TPMS Car Tire Pressure -Solar power charging, don't need to charge by connecting car cigarette lighter -Rear-time monitoring pressure & temperature of 4 tires -Low air pressure/high temperature alarm -High Temperature / Leakage / Low Battery Alarm -Intelligent Shock Boot when car moving, don't need to turn on/off Specification: Adhere to windscreen for installation Operating frequency: 433.92Mhz 50KHz Operating voltage: 3.7-5 V Working temperature: -20 -75 Pressure Range: 0.5-3.5 Bar Reading difference for external sensors: 0.3 bar / 4 PSI Reading difference for internal sensors: 0.1 bar / 2 PSI Questiosns & Answers 1. How to turn on the device? When you receive the device, please charge it for 3 hours, then, long press left button to turn on the device. 2. The sensor is showing''0.0'' or ''-'', what can I do? Under this situation, we should try to install the sensors again or pair the sensors to the display again. If you don't know how to do pairing, please check the manual or , we will guide you. 3. What's the difference for external sensors and built-in sensors? -External sensors are easy to install, they have 0-0.2 reading difference. The battery inside is replacable, battery lifetime is about 1 years, battery type is CR1632. -Built-in sensors could detect accurate reading, battery is not replacable, battery lifetime is about 4-5 years. 4.What's the pressure tange? The range is 0.5-3.5 bar 5.What's the unit using in this device? Bar or Psi, the unit could be switched to the one you like.