This is a 2 channel DWDM mux demux that operates over channels 27-28. It also has a monitor port, and an express port. This unit can be used as either a multiplexer or de-multiplexer (mux/demux), and is a plug and play system. All of our mux/demux products are 100% compliant and provide a cost effective solution for your network upgrade needs. With our certification test program, we guarantee your product will work correctly the first time.