Hi, I have a Buffet B flat clarinet that according to the serial number was made in the 1950’s. It has the extra fourth finger ring around the hole for the left hand and the right hand lower piece has the extra fifth key. There is no model number on the instrument. As I no longer play it, I would like to know the model number so that I can determine a fair asking price for it. If you can provide any information or tell me where to find info on it, I would appreciate it very much.