I Have to Ask?

At the top of the page you'll see steady Teddy in the add about signing up for the Pyamyd Cup with his usual grin on his face. Will someone enlighten me on what the heck he has on top of his breech to mount the scope with. Can't see how you could shoot through the scope with any kind of cheek weld. Surely not intended for that purpose I presume.
Confused,
Jimmy