Works on any two or more conductor cable up to 2500 feet. Instantly measures distance to open or any fault from one end of any cable pair. Patented SmartTone tone generator positively identifies pair. Measures cable distance on spool. Measures constantly while "On". Displays distance reading rather than waveform. Large LED screen. High voltage detection. Moisture proof. One-button operation. Additional line cord options available for coaxial cable (f-connectors) and other applications. .