Features: The two wire are used regularly. The redness connection to the positive, the black connection to the negative, and the reverse connection protect. Normally, no external working power-supply need, and the measuring voltages can be directly operated. The measuring voltages ranges: 5V-19.9V. Bright LED display, the strong plastic case prevents it from easily damaged by outer force. Operating voltages: no need to connect to any power-supply, two-wire systems. Suitable for most vehicles, such as automobiles, ship, substation-automation, distribution-automation, test equipment. its practicability enough to meet your various-need. Specifications: Material:ABS Detection Voltages:5V-19.9V LED Color: Redness/ Green / Blue Size:Approx.5.6x2.9cm Cable Length:Approx.70cm/27.56'' Package Includes: 1Piece Digital Voltmeter note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual color.