USB PORT - The car voltmeter is designed with a USB charging port that can be used to charge smartphones, GPS navigators, tablets, etc. MEASURING TEMPERATURE - The measurable temperature range of this car charger is -10-80 C. In order to measure the temperature accurately, the temperature sensor is external, soft and flexible and easy to hide. Keep the sensor away from hot vehicle parts. VOLTAGE MEASUREMENT - The car voltage meter can be used for 12 V cars and SUVs, as well as for 24 V trucks and buses. Reliably reflects the car battery voltage. If the voltage is below 12.5V, please stop using electrical appliances to avoid difficultystarting the vehicle. CHARGING POWER - 5V 2A is suitable for the charging power of most cell phones and the charging speed is the same as or better than conventional charging heads. The LCD screen shows the voltage and temperature in the vehicle in real time to avoid excessive power consumption and ensure the safety of the vehicle.