You need more double wires.
Power supply is necessary.
Power reverse connection protection.
Wide working voltage range.
Temperature coefficient: 25ppm/ Celsius
Range: 0-33.000V DC
Precision: +/-2 digit,0.3%
Operating temperature: 10 Celsius~65 Celsius
Power supply voltage: 4 to 30V
Red line: power + (3.5-30v).
Wiring: power, black
Measures: the line (0-33.000v + yellow).
Product weight: 15g
colour:black
Material:PC+ metal
size:Type: LED 0.36 inch 5 bit
Package Contents:
2 x Voltage Meter
2 x Connecting Cable