CWDM stands for Coarse Wavelength Division Multiplexing. It is a technology that allows simultaneous wavelengths (channels) to travel over the same optic fiber, thus enhancing the capacity of the fiber. The combination is possible by using passive optical filters (mux/demuxes). There are currently 18 CWDM channels being mostly used, with the 1471~1611nm 8 channels segment being the most used of them. Section includes regular Gigabit speed, multi-rate 155M-1.25G and multi-rate 2.67G transceivers. The 2.67G units can be used in either Fast or Gigabit Ethernet, OC3, OC12 or OC48 connections. They can also be used in 1G or 2G Fibre Channel connections and many others. CWDM channels have a spacing of 20nm between them. All models have Digital Dignostic Monitoring features (SFF-8472 compatible).