 Many CWDM wavelengths below 1470 nm are considered unusable on older G.652 specification fibers, due to the increased attenuation in the 1270–1470 nm bands.Newer fibers which conform to the G.652.C and G.652.D standards, such as Corning SMF-28e and Samsung Widepass, nearly eliminate the "water peak" attenuation peak at 1383nm and allow for full operation of all 18 ITU CWDM channels in metropolitan networks.The main characteristic of the recent ITU CWDM standard is that the signals are not spaced appropriately for amplification by EDFAs.