Introduction of the key: Right Select Key: Select key of menu M Menu Key: Long pre into menu setting Left Select Key: Long pre to turn on/off, Select key of menu Features: Type: Intelligent Solar TPMS Car Tire Preure Solar power charging, dont need to charge by connecting car cigarette lighter Colorful LCD Digital displaying, clear to show tire information Rear-time monitoring preure & temperature of 4 tires Low air preure/high temperature alarm High Temperature / Leakage / Low Battery Alarm Intelligent Shock Boot when car moving, dont need to turn on/off Wirele connect by sensors, easy install Two units (PSI / Bar) changeable, you can set the one you like. External Sensor: Easy to install, convenient to replace Battery: built-in CR1632 button cell Working voltage: 2.0 - 3.6V Working environment: -30 ~105 Deg.C Preure accuracy: plus or minus 0.1bar Waterproof grade: IP67 Transmiion frequency: 433.92MHz Monitor: Battery type: 280mAh Li-ion battery Working voltage: 2.6-3.6V Working environment: -20 ~70 Deg.C Transmiion frequency: 433.92MHz Preure unit: psi / bar Temperature unit: Deg.C / Deg.F Package Included: 1 set Car Tyre Preure Monitoring System