The 4ch(8waves) DWDM MUX/ DEMUX with Blue and Red（R/B）filter, is used in pairs, designed by FIBERWDM, in side A, the waves are: RX C21 to C24, TX C45 to C48; And in side B, the waves are: RX C45 to C48, TX C21 to C24. it conjunct with the DWDM amplifiers and DCM device, the 4ch DWDM transfer system can support a long distance transmission in one fiber. And it is LGX box Plug-in designed, so it can plug in the 4-Slot 1U rack, Max capacity support 4*4channels in the system.