Snould be here

https://www.sonos.com/en-us/myaccount/system/households/devices

I don’t believe there has ever been another generation of the Sonos One SL … only the Sonos One was updated to gen2, that’s also been replaced now by the Era 100.

See the details published here for Sonos products and their release dates…

https://en.wikipedia.org/wiki/Sonos

Ken, Stanley, Thank you this is very helpful

I found some more info. Although the One SL has not had a ‘generation’ change it seems there were some (presumably) minor changes to it. Another user here in the community mentions this…

There are three versions of the One SL: S22, S38 and S43, the model # should be on the base. S43 is new and is S2 (Sonos App)-only.

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Although the early One SL was available for a Sonos S1 system, once it had been updated to an S2/Sonos App System setup, there is apparently no way to return it to an S1 setup.

Hope that information assists here too.

Yes, thanks. I also spoke with Sonos yesterday. After waiting an hour on hold, they said I couldn't add any Sonos One SLs to my existing S1 system. However, a Sonos One (gen 1 or 2) will work for me. So, I ordered a Gen 2 from e-bay. It should work, but I've got my fingers crossed.

If it has previously been installed on S2 and you need to downgrade the Sonos One (gen2) to work on S1, then here are the instructions to be able to do that…

https://support.sonos.com/en-us/article/downgrade-a-sonos-product-to-s1

Thank you