- Tight clamped port for reliable interfaces: compatible with network cable interfaces and RJ11 two-core telephone lines, connectable via crocodile clip line. - Network cable calibration and continuity testing: insert the cable ends into the transmitter and receiver interfaces respectively, set the transmitter to “line,” and use the Line Light to determine line continuity and detect shorts. - Polarity and DC level testing: switch to “Line Hunting,” press and hold the Switch for more than 2 seconds until the Line Light flashes, then insert both ends of the clips into the RJ11 socket and power supply. - Clear listening in noisy environments: includes a headphone cable for operation in loud settings, with volume adjustable by the knob. - Front illumination for dark work: in dim conditions, flip the receiver light switch upward to illuminate the front panel. Use scenarios: - Verify RJ11 telephone line polarity and continuity during installation or repair. - Test network cables for proper connection and detect shorts or open circuits on site. - Perform inspections in low-light environments using the built-in flashlight and headphone monitoring for clarity.