Ingco Digital AC Clamp Meter.

A clamp meter is an electrical test tool that combines a basic digital multimeter with a current sensor.Clamps measure current. Probes measure voltage. Having a hinged jaw integrated into an electrical meter allows technicians to clamp the jaws around a wire, cable or other conductor at any point in an electrical system, then measure current in that circuit without disconnecting/deenergizing it.
Beneath their plastic moldings, hard jaws consist of ferrite iron and are engineered to detect, concentrate and measure the magnetic field being generated by current as it flows through a conductor.Clamp meters are highly efficient at safely and speedily measuring current, without interrupting the current flow or using test leads. The clamps measure current such as AC current, AC and DC voltage, resistance, and continuity. Some models can also measure DC current, capacitance, temperature, and frequency.