This is Red-Blue LED Digital Dual DC 100V 10A Ammeter Voltmeter. This meter will measure up to 100 VDC with a 0.1-volt resolution. Specification: 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.