Just checked your profile thread and I see you have an after-market exhaust
(

pushki, I'm shocked!

)
In that case, that would explain why it has gaskets instead of crush rings. My ebay jobber stainless manifold/downpipe (in the shed waiting to be fitted) came with a gasket to join onto the cat. They're probably just cheaper/easier for aftermarket exhaust manufacturers?
Dunno where you'd get one of them without looking (as it's not the standard kit I mean).
If the pipe diameter and flanges are the same though, the standard crush rings might still be fine?