Wavelength on an SFP

[echipbk12]

1. A label of an SFP is as below:
Cloudtron SFP-1G-1490-24dB-D
Is the wavelength 1490 nm used for both transmitting and receiving?
And since there is only one wavelength on the label, is this a Grey (standard) transceiver compared to a xWDM?

2. a CDWM SFP has only one wavelength printed on the label as per below:
Cloudtron SFP-1G-C-41dB-G-D-25, CWDM, 41dB, 1390nm
Since only one wavelength is on the label as per above. Does it mean it can only support one wavelength? As per what I knew, xWDM transceiver can support multiple wavelengths, so what's the point of supporting only one wavelength and being classified as CWDM?

[Tom Randstrom · Accepted solution]

Take a look at the following reference document for CWDM.  It helps explain the CWDM solution, which uses CWDM compatible optics and mux/demux devices to add and drop the individual optical signals from the fiber link. 

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/cwdm-transceiver-modules/product_data_sheet09186a00801a557c.html