ATOP offers DWDM MUX/DEMUX in the form of 1U 19” rack mountable box with 4 channel configuration, 40-Channel, 16-Channel, 8-Channel, and 4-Channel; and CDWM MUX/DEMUX with 2 channel configuration, 16-Channel and 8-Channel. They are modular, compact and scalable with low insertion loss and excellent anti-interference ability. They are perfectly suited to transport PDH, SDH/SONET, Ethernet services over WDM in optical metro edge and access networks.