This information is from an eBay listing.
Here is an extremely rare example of a mid 19th century, Civil War era metal clarinet. The body of the clarinet is brass. The keys, rings and thumb rest are nickel silver (German silver). It has 7 keys and 8 holes. The body is one piece. The body does not separate in the middle and the bell does not detach. The mouthpiece receiver moves for tuning. It has waxed string on the tenon that receives the mouthpiece receiver. All keys move freely and have springs. The body appears to be straight. The mouthpiece receiver is mostly round, but a couple of spots on the edge are slightly bent in (see photo). Everything is original except for the key cover closest to the bell. It was missing. I had Mark Metzler make a replacement. Mark has extensive experience repairing and restoring antique wind instruments. The overall length of this clarinet is approximately 16.85 inches, which would make this an E-flat clarinet. The opening for the mouthpiece measure approximately .725 inches. The bell diameter is approximately 2.15 inches. I cannot find any maker’s markings. Sorry, no mouthpiece.