This is Red–Blue LED Digital Dual DC 100V 10A Ammeter Voltmeter. This meter will measure up to 100V DC with a 0.1-volt resolution.
One thing to note is, this meter has 2 wiring harnesses. One harness is to provide power for the meters, that’s the 2 poles with a RED and a BLACK lead. Small size, portable, the magnitudes of voltage, and current are displayed on the same screen at the same time.
Digital Voltmeter is an instrument used to measure the electrical potential difference between two points in a circuit.
Digital Voltmeter displays the voltage readings of a circuit numerically.
Digital Voltmeter is used to know the actual voltage of different components.
DVM is widely used to check if there is power in the circuit, such as the mains outlet.
Knowing the voltage across a circuit, current can be calculated.