What does this overflow pipe connect to below the cistern?

[Chris Green]

I need to replace my existing overflow pipe in my toilet cistern, the bottom end has split.

Screwfix have something similar to what I need:-

... but it's not clear how it connects below the cistern. My existing stand pipe has a 21.5mm compression connection at the bottom but it doesn't look as if this is what the above Screwfix on has. Can anyone tell me how the Screwfix one connects to ongoing pipework?

[spuorgelgoog]

One of the reviews says "standard threaded connection"

(*which* standard isn't said).

Owain

[Chris Green]

But waste pipe doesn't usually have any sort of threaded connection!

I can see a few on eBay which seem to have a compression joint at the bottom but I can't find anything which explicitly has 21.5mm compression. What I can't fathom out is why one could possibly want any other sort of connection.

[Iggy]

replying to Chris Green, Iggy wrote: It could be a separate pipe like the Screwfix one, but most commonly it's all

1-piece with the entire flush valve needing to be replaced. Like, this OR THIS OR THIS