Thank you for viewing. Gotts Alto Saxophone Mouthpiece Marble Jazz Soloist C⭐︎⭐︎ The C⭐︎⭐︎ opening is 1.8mm, the same as a Meyer 5. I usually use a Meyer mouthpiece and haven't used this much. There may be some minor scratches from testing, but please refrain from purchasing if you are concerned. It produces the characteristic good sound of the Marble Soloist, but I seem to prefer Meyer, so I've decided to sell it. Please consider it. Also, please see the profile section before purchasing.