seal on dirt bike carburettor question?

[Cieran S]

I recently took apart the carburettor on my dirt bike to clean it.I put it all back together but then i found a little round seal on the table i was cleaning it on.I dont know where the seal goes.It is about 3 or 4 mm...It probably fell off while i was spraying a part of the carb.If anybody could tell me where it goes i would be delighted...Thanks