The Extech CT20 Continuity Tester Pro allows one person to perform wire and cable testing, even when ends are in different rooms. It verifies local continuity with a bright flashing LED and 85dB pulsating beeper. For long-distance runs, the remote probe with bi-color (red/green) LED identifies up to three wires simultaneously, eliminating multiple trips. Polarity verification drives a 20mA DC current pulse to the remote probe. Maximum wire verification distance is 10,000 ft (3,000 m) with minimum 26 AWG cable. Includes main tester, remote probe, test leads with alligator clips, 9V battery, and pouch.