Baluns are employed in data circuits to act as an interface between twisted wire pairs and coaxial circuits. The GB422M consists of a plastic rectangular housing enclosing a nominal 93-ohm, transformer-type balun connected to a coaxial connector on one end, and to a 6-position, 2-conductor modular jack wired to pins 3 and 4 on the other; voltage breakdown and leakage values are well within telephone standards. Screw terminals are also provided on the modular (twisted pair) side for testing or direct connection. Estimated operating distance on 24-gauge twisted pair cable will run from 1300 to 1500 feet.