The TUNOP cards are optical transmission units available in two hardware versions. The first, TUNOP-1 has a single 4 x 2Mbps optical port for transmission up to 8Mbps. The second card, TUNOP-2 has two 8Mbps optical ports with a maximum throughput of 8Mbps (throughput can be split between each port in multiples of 2Mbps)

Each port can be individually configured and activated.

The 2 port version allows for any 2Mbps signal to be transparently switched from one port to the other. Thus drop and insert, Drop off and Bypass configurations can be implemented.