Vktech&reg; Auto Car Voltage Digital LCD Temperature Thermometer Alarm Clock Time/date,switch from 12 hour to 24 hour system conversion Alarm clock and extending 5 minutes reminding function. Temperature Can be Switched From the Display Deg.C to Fahrenheit LED will be in a back light when using car power supply, and can display LCD full content. If using a spare battery power supply, not back light, LCD only display time and internal and external temperature Temperature sampling every 60 seconds