Functions and Features： -Solar power charging, don’t need to charge by connecting car cigarette lighter; -Colorful LCD Digital displaying, clear to show tire information; -Real-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, doesn’t need to turn on/off; -Wireless connection by sensors, easy to install; -Build-in sensors and external sensor options, meet all your needs; -Freescale chip sensors fit on almost 98% of cars on the market; -Easy to install, convenient to replace; -Dust-Proof / Water-Proof / Anti-theft; -Anti High Temperate and Cold; -IP67 Protection / Waterproof; Specifications: Working voltage: 2.1-3.5V Pressure accuracy: ±2psi Frequency:433.92 ΜΗΖ Pressure rate: 0~3.5Bar/0~50psi -Working Temperature: -20℃-80℃; How to replace the External Sensor battery? 1. Remove the dismantling gasket； 2. Wrench the shell with a wrench； 3. Remove the battery； 4. Replace a new battery. Note： Please turn on the monitor before installing the sensor： 1. Press and hold on the power button to turn on the monitor 2. Install External or Built-in sensors one by one Package includes: 1x Solar Tire Pressure Monitors 4x External sensor 1x Fixed sticker 1x Screw nut 1x Wrench 1x USB power cable 1x Instructions