Holdding Fahrenheit Scale &deg;F 0.56" DC 12V Digital Car Clock Thermometer Voltmeter 3in1 Blue LED Auto Gauges DS18b20 Electronic Clock with Anti-reverse Protection Probe Power Supply voltage: DC 7-30V (with anti-reverse protection) Measuring temperature: -67F to 257F Measuring voltage: Range 0-200VDC, Accuracy +/-0.1V Clock: 24-hour, the battery backup is available 3-4 years Display: Four 0.56 "LED digital tube