GEREE Dual Display Volt Amp Voltmeter Ammeter 0.28" LED Digital DC 0-100V/50A Voltage Current Measurement Meter with Shunt GEREE Volt Amp Voltmeter warranty--30-Day Money Back Guarantee -- 12 Month Replacement Warranty -- Lifetime Support Guarantee DC 0-100V/0-50A measuring range; DC4.5V - 30V power source. 48x29x21mm dimensions, small size, easy to mount. 0.28" Digital Tube with clarity and brightness LED display. Ground wire of testing end and power supply temninal is the same wire; quick refresh of about 500 ms.