[Gaz64]

Yes, I thought that's what you would looking for.

That stick-on piece is used on manual choke carbs to seal a manifold vacuum source that is used for automatic choke models.
It comes as a sticky, to help assembly. You can make it yourself, out of a piece of gasket paper, and bond it with a smear of contact adhesive.
The clamping of the manual choke assembly mounting keeps it sealed.

Gary