This Otto Link Reso Chamber mouthpiece for Tenor is sort of a strange bird. As you can see from the pictures there is no serial number, or the typical Otto Link Co stamp on the shank. We believe someone buffed these off sometime age. The piece has also been worked on by someone previously, and they even stamped the 7* facing on the table. The piece definitely has the nice dark sound you would expect from a good Reso Chamber mouthpiece, and it's even a little more comfortable than usual with the bigger tip opening.