25G DWDM SFP28 is a high-precision, hot-pluggable optical transceiver designed for Dense Wavelength Division Multiplexing (DWDM) systems. It transmits a 25 Gbps data stream on a specific, tightly spaced wavelength.Multiple 25G DWDM SFP28 transceivers, each emitting a different but closely spaced wavelength, have their signals combined by a DWDM multiplexer.