This is a Fluke 773 Milliamp Process Clamp Meter.
It is used mainly by electricians, instrument technicians, and engineers to test and troubleshoot industrial control systems.
What it is used for
* Measuring 4–20 mA signals in industrial equipment
* Testing sensors, transmitters, and PLC systems
* Troubleshooting automation and process control equipment
* Measuring current without disconnecting wires (using the clamp)
* Supplying or simulating current signals during calibration