Introduction of the key: Right Select Key: Select key of menu M Menu Key: Long press into menu setting Left Select Key: Long press to turn on/off, Select key of menu Features: Type: Intelligent Solar TPMS Car Tire Pressure 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 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 Pressure accuracy: plus or minus 0.1bar Waterproof grade: IP67 Transmission frequency: 433.92MHz Monitor : Battery type: 280mAh Li-ion battery Working voltage: 2.6-3.6V Working environment: -20 ~70 Deg.C Transmission frequency: 433.92MHz Pressure unit: psi / bar Temperature unit: Deg.C / Deg.F Package Included: 1 set Car Tyre Pressure Monitoring System Do drop