Cisco SFP compatibility question

[GIdenJoe]

HI all, I'm hoping to get an answer for this question from someone with experience or from Meraki itself.

In the documentation: Small-Form Factor Pluggable (SFP) and Stacking Accessories - Cisco Meraki Documentation

It says it is compatible with most Cisco SFP's but then it says fixed wavelength.

- What would be an example of a variable wavelength optic?

- Previously I was told from Meraki that BXD SFP's are fully compatible with C9300-M and these use two different wavelengths for TX and RX.  So does this qualify as fixed wavelength?

[cmr]

@GIdenJoe it isn't something I'd heard of before, but it seems they are a thing!  See this link from FS: https://community.fs.com/article/tunable-optical-transceivers-what-are-they-and-when-should-they-be-...