Technical parameters: Operating Current: Display: 0.28 "LED monochrome (all red) Dimensions: 48 x 29 x 21mm Installation hole: 45.5 x 26.5mm Measuring rate: 500mS / times Accuracy: 1% (+/- 1 word) Extreme working conditions: Minimum operating voltage: +4.5V Maximum working voltage: +30V Working temperature: -10'C~+65'C Operating Humidity: 10~80% (non-condensing) Working pressure: 80~106kPa Sun exposure: no direct exposure The table with promising three wires easy access to 4.5~30V voltage range car / battery car / motorcycle-car line is used to monitor the battery voltage battery voltage status grasp can also be used for other products voltage and current measurement purposes