Description of 4-in-1 design: clock, indoor and outdoor thermometer, voltmeter, antifreeze alarm. Drive the car, the built-in battery can continue to work without backlight after a power outage and power the car. Indoor/outdoor thermometer: Fahrenheit and Celsius modes selectable, range from -50 to 158. Digital clock: Select 12/24-hour mode. Small size, easy to install in the car, large LCD screen and blue/orange backlight, easy to see. Exhibition: Large LCD screen; Blue and orange backlight options; Clock function: Calendar: days and dates 12/24-hour mode; Snooze alarm function, after 5 minutes, snooze time: 5 minutes; Thermometer function: Fahrenheit and Celsius adjustable; Outdoor and indoor temperature monitoring; Accurate temperature: ±1.0? Temperature measurement time: 60 seconds DC voltmeter function: 12V Function buttons: Time: change day and date. Press for 2 seconds to enter time setting mode; ALM: Displays alarm time. Press and hold for 2 seconds to enter alarm setting mode: up arrow +1. In alarm setting mode, click to turn on/off alarm sound. 1 x 4 in 1 Car Tester Key points: 1. The product size is measured manually, there may be some errors 2. Since different monitors display different colors, please refer to the actual color you received. 3. Please confirm the size before purchasing. 4. After receiving the package, if there is any dissatisfaction, please contact me first, do not leave a bad review easily, thank you, I wish you a happy and very rich.