NEC DSX-80/160 16-Port Digital Station Card - 1091004
The 16ESIU has a Mode Switch (for taking the card out of service). It also has a status LED that indicates proper card operation — as well as a port activity LED that flashes faster as traffic on the card increases. You can install up to two 16ESIU Cards in a DSX-80. You can install up to six 16ESIU Cards in a DSX-160.