It is a Digital Voltmeter/Panel Meter/Tester, Measuring Voltage Range: AC 0 to 500V ( Need Extra Power Supply ), Power Supply Voltage: DC 9~12V, It has 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 and All kinds Voltage Measuring.platforms.