It is Digital Meter/Voltmeter/Tester, Measurement voltage range: DC 0~99.9V (need extra Power Supply DC 5~28V), Power Supply: DC 5~28V, It has Reverse polarity protection, small size, high efficiency, long term stable and reliable quality,easy installation and use. Application: industrial equipments,electronic equipment, Power distribution box, distribution cabinet, regulators, teaching aids, household small distribution box, Car / battery car / motorcycle battery and All kinds Measuring.