Baluns allow you to run an ARCnet™ or IBM™ 3270 coax type signal through twisted pair wire. Two would actually be needed to make a connection, one at each end of the twisted pair wire. The active pins are 3 and 4. The twisted pair wiring is straight through (3-3, 4-4).Please note: Baluns are not signal converters and won't work to convert from Arcnet™ to Ethernet™.