Description:  Real time Monitor tire pressure can improve fuel efficiency, prolong tire life, increase traffic safety and monitor temperature.  Visual and sound warning.  LCD displays tire pressure and temperature.  Wireless connect by sensors, easy install.  Solar charging,don't need to connect car cig lighter to charge.  USB charging available,no worried when rainy day or night time.     Specifications:  Color: Black.  Sensor IP: IP67.  Display Units: Bar, Psi.  Size: as the pictures.  Material: Plastic, metal.  Working Frequency: 433.92MHz.  Sensor Working Temp.: -40~125 °C.  Receiver Working Temp.:  -20 ~ 70°C.  Working Pressure: 0~51 Psi/0~ 3.5 Bar.  Receiver charging method: USB, Solar energy.  Working Voltage: Sensor 2.0-3.6V,Receiver  5V.  Sensor Battery: Built-in CR2050 button battery.  Receiver Battery: Built-in 400m Ah polymer lithium battery.     Tips:  The host (TPMS) must be turned on before installing the sensor (long press the left button for three seconds to turn on and off).  It is recommended to use a mobile phone charger or car charger to charge the new machine for 1 hour before using the new machine.  During normal use, when you open the door before getting on the car and start the car, the host (TPMS) will automatically wake up the screen when it receives a sense of vibration. After getting off the car, the host (TPMS) will automatically turn off the screen and enter the parking dormant state after the car is stationary for about ten minutes.     Package:  Internal: 1x Solar powered Monitor;  External: 4 x Solar powered Monitors