I believe the clarinet is a Buffet R13, early 1960s, S/N 63xxx.
A couple of features on the top joint that I need help with:
There`s a ring round the lowest tone hole which closes the little key between the top and middle tone hole, which I don`t see on photos of R13s. An intonation enhancement ?
The middle tone hole has a big wide padded ring with 3 little adjustment screws which closes the same key as above. Why so big and padded ?
The register key which you operate with your thumb at the back is on the front, attached to a long curved arm. Is this usual for this date ?

Any enlightenment from the experts would be much appreciated.

sometimes the picture on the web for the instrument isnt the actual instrument....its another similar one.

No, I`ve handled the one with the extra rings etc., looking over it prior to possibly buying it. I was hoping to find out if these features are particularly advatageous. Researches have merely brought up loads of pictures of R13s, none of which have them.