DROK Micro Voltmeter Current Meter Digital Voltmeter Gauge 100V /50A DC Current Meter LED Display Auto/Car/Eletronic Voltage Meter with Transformer (50A) It is tiny and small; dual display of current and voltage in the same time It adopts excellent SMT technology and hence has good consistency With voltage and current potentiometer for adjustment in avoid of error It has a speacially designed hole for leading wire; dont need to cut/damage/change its original circuit for current measurement Don't need to worry about "common ground" of current meter and you can test current in postive pole/negative pole of power supply or current of certain wire/equipment casually because its current sensor is totally separated from eletric of tested leading wire