Display on the same screen: hours, minutes, seconds, weeks, indoor temperature, outdoor temperature, and voltage. 12/24H: It can be switched between 12/24 hours, and can be equipped with alarm clock and snooze function. Temperature measurement: Temperature can be switched to display Celsius or Fahrenheits degrees, and temperature measurement range: - 50 to 70 degrees Celsius. The sampling period for temperature measurement is 20 seconds. LED backlight function: When powered by a car, there is backlight, and the LCD content is fully displayed; When powered by a backup battery, there is no backlight and the LCD only displays the time. Frost alarm function: On the interface displaying the time, press and hold the Celsius and Fahrenheits switch button for 2 seconds to turn on or off the indoor and outdoor frost alarm. When the frost alarm function is turned on and the temperature is within the range of - 1-4 degrees Celsius, an alarm will be issued for 30 seconds, and its flag will flash. Specification: Material: plastic+metal Size: Approx.15.5 * 3.40 * 2.2cm/6.10 * 1.34 * 0.87 inches Backlight: blue, green (switchable) Sensor cable length: 300cm Vehicle charging line length: 2M Working voltage: DC 12.0V Temperature switchable display / Temperature measurement, measurement range: - 50 ~70 Temperature display resolution: 1 , temperature accuracy: 1.0 Temperature measurement sampling cycle: 20 seconds Package Includes: 3 options for you as bellow 2PCS : 2 set of 3PCS : 3 set of 1PCS : 1 set of