"One channel DWDM OADM, Band 7, Channel 7 (1554.94nm) (ECI)" is marked on product bag of one system sample. We opened this system, there is an optical module of Oplink P/N: DWDMG01C28BTI12. We checked its passband spectrum by Optical Spectrum Analyzer very approximately, the bandwidth is about 0.8nm at -12dB with flat passband, so we very believe it is for 100GHz-spaced DWDM. Based on our test, we found it is actually two OADM modules. One optical add module includes "pass through Input", "Line Output", and "Add" ports. One optical drop module includes "Pass through Out", "Line Input", and "Drop" parts. "Pass through Out", and "Drop" ports are covered with LC terminals. With 6 LC/PC adapters at front panel. See ITU grid definition in the pdf link below. Oplink P/N: DWDMG01C28BTI12 module is all-optical passive. 

There are other products with different wavelengths. Product options:
Add and drop wavelength 1554.94nm. ECI TELECOM P/N: BP1A36AA-07-E. "One channel DWDM OADM, Band 7, Channel 7 (1554.94nm) (ECI)"
Add and drop wavelength 1558.17nm. ECI TELECOM P/N: BP1A36AA-03-E. "One channel DWDM OADM, Band 1, Channel 3 (1558.17nm) (ECI)"
Add and drop wavelength 1546.92nm. ECI TELECOM P/N: BP1A36AA-15-E. "One channel DWDM OADM, Channel 15"
Add and drop wavelength 1546.12nm. ECI TELECOM P/N: BP1A36AA-16-E. "One channel DWDM OADM, Channel 16"
Add and drop wavelength 1557.36nm. ECI TELECOM P/N: BP1A36AA-04-E. "1 channel DWDM OADM, band 1, Channel 4 (1557.36nm)(ECI) "
Add and drop wavelength 1558.98nm. ECI TELECOM P/N: BP1A36AA-02-E. "1 channel DWDM OADM, band 1, Channel 2 (1558.98nm)(ECI) "
Add and drop wavelength 1547.72nm. ECI TELECOM P/N: BP1A36AA-14-E. "1 channel DWDM OADM, Channel 14 "