18 LEDs (9 Green, 9 Red). Pins monitored are 2 (TXD), 3 (RXD), 4(RTS), 5 (CTS). (DSR), 8 (CD), 20 (DTR), 11 (HS), 19(HS) . All lines are wired pin to pin. The unit has a 25-way ‘D’ connector M-F line installation. 500 mating cycles. 30V operating voltage.