1. Display: digital form2. Material: shell ABS3. Voltage: 12V / 24V4. Size: about 4.3 cm in diameter5. Connect power: plug and play cigarette lighter6. Function: measure the voltage to avoid excessive power consumption; measure the temperature to make the temperature in the car more comfortable; USB charging, mobile phone charging is more convenient

http://olla.gr/3-in-1-car-usb-charger-car-cigarette-lighter-with-voltage-detection-display-multi-function-monitoring-table-red/