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 4 and 5. The twisted pair wiring is straight through (4-4, 5-5).Please note: Baluns are not signal converters and won't work to convert from Arcnet™ to Ethernet™.