This is a Fluke 707 Loop Calibrator, a handheld professional instrument designed primarily for testing, sourcing, and measuring 4–20 mA current loops used in industrial automation and process-control systems.
Model: Fluke 707 Loop Calibrator
Display: Large LCD at the top for showing the measured or sourced current.
Rotary control: The large center dial provides fine adjustment of the loop current.
MODE button: Used to select operating functions.
25% button: Provides quick 25% step adjustments.
0–100% button: Allows quick movement through the loop's 0–100% range.
Power button: Green button at the upper right.
Terminals: COM and + connections are visible at the bottom.
100 mA marking: Indicates the current-related input/output section of the instrument.