"NEC 1091004 Brand New Includes Two Year Warranty, The NEC 1091004 16 Port Digital Station Card connects 16 digital extensions
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. 1091004 Features: DSX-80/160 16-Port Digital Station Card, Provides 16 Additional Digital Station Ports, Mode Switch, LED Indicator"