Hi Pilou, you can also select the top and bottom faces and use the Shell command to make an opening like that. That way you only need to enter in wall thickness, not height.

- Michael

good tip Michael
thanks :)

<< That way you only need to enter in wall thickness, not height.

But selecting 2 faces! - Inset: only one face for the same result! ;)

And with many more variations if needed! :)
Here Select only the Top's Start Cylinder Disc!