Please note , the battery is built in the external Specifications and functions -Solar power charging, dont need to charge by connecting car cigarette lighter -Colorful LCD Digital displaying, clear to show tire information -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, dont need to turn on/off -Wireless connect by sensors, easy install -Build-in sensors and external sensors options, meets all your need -Freescale chip sensors and fit on almost 98% cars on market -Host setting range:1.1Bar-6.7Bar/0.11Mpa-0.67Mpa/15.95psi-97.15psi Build-in Sensor ( Optional ) -Please install in by Professional car center -More stable and accurate -Anti High Temperate and Cold -IP67 Protection / Waterproof -Working Temperature: -40-125 -Battery Life: 5 Years;Not replaceable External Sensor (Optional) -Easy to install, convenient to replace -Dust-Proof / Water-Proof / Anti-theft -Anti High Temperate and Cold -IP67 Protection / Waterproof -Working Temperature: -20-80 -Battery Life: 2 Years, replaceable 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.