Introduction of the key: Left Select Key: Long pre to turn on/off, Select key of menu M Menu Key: Long pre into menu setting Right Select Key: Select key of menu Descriptions: Black and white screen, the effect is better than color screen under the sun, and it saves more power than color screen; Tire preure alarm, solar charging, wirele transmiion. Simultaneous monitoring of 4 wheels; Prevent problems before they occur: avoid punctures and leaks and balance air preure, saving fuel and reducing wear; Sensor: internal/ external; ready to use, four-wheel display; Features: High-efficiency solar panel, long battery time; Large-capacity built-in metal lithium battery, uninterrupted battery life on cloudy days; Accurate monitoring of tire preure and tire stability throughout the proce; High precision display; Large volume alarm tone warning; Multiple tire preure units are available; Long receiving distance and stable signal; Supports tire position interchange. Specification: Product colour: Black Air preure setting range: 0.1 ~ 5.9Bar Temperature setting range: 60 ~ 110 Working temperature: -20 ~ + 80 Storage temperature: -30 ~ + 85 Power-on voltage: DC 5V Frequency: 433.92 MHz 20.00 MHz Product size: 95 * 70 * 25 mm/3.74*2.76*0.98" Sensor type: Internal/External Internal Sensor: Bttery life of about five years, and the battery can be replaced (replace the valve core of the original car, and balance it after installation.) Using airway alloy gas nozzle; Japan imported battery; The shell is made of nylon chemical fiber material to prevent corrosion; Adjustable angle link between the air nozzle and the sensor, to ensure that the angle is adjusted to be flush with the edge of the groove during installation. External sensor: Battery life is about two years, replaceable (installed on the valve core); The surface of the shell is anti-corrosive coating; Using hexagonal nut anti-theft patent; Using unique external tire preure sealing and ventilation mechanism patented silicone integrated molding structure to prevent air leakage; Package Included:: 1 set*Internal sensor / 1 set*External sensor