Full Plateau Unibody Buffet A Clarinet with Donut Key

Here is an interesting piece.

This Buffet Crampon A clarinet is a unibody, featuring full plateau keys with one "Donut" key.  
The donut key was somewhat popular among Buffet products (see Buffet G Fischer and Buffet Antique Unibody pages) during the early 20th century, from approx 1910-1920 (or so).
Better yet, it features an articulated C#/G# key.

This clarinet currently resides in the collection of David Watson of San Diego, California.