KAMSOL 2 in 1 Backlight Mini Electronic Clock with Thermometer Digital LCD Display for Car Air Vent Size: Length 3.2 x Width 0.7 inches. After press the button on this car clock, the blue back-light is maintaining 5 seconds. Car clock power type: by button battery. Clip stick on the Air vent, easy and convenient to install and read the data. Temperature detection range: 0 to 50 Celsius Degrees. Note: Not Fahrenheit Degrees.