I defer to wonky donky's greater knowledge of match airguns and diopters than mine and I don't doubt that what he says is true. All I know is that I've seen several of this model of Hammerli rear sight for sale on egun, advertised as being suitable for 11mm dovetails.

eg.
http://www.egun.de/market/item.php?id=2611555
http://www.egun.de/market/item.php?id=2594716