Thank you for viewing. This is a Greg Black large-shank tenor trombone mouthpiece, the Finlayson model. * 4G-5G Medium .295 David Finlayson, 2nd trombone player of the New York Philharmonic, model. This has a 4G rim diameter with a slightly thicker throat. The depth is 5G, so it gives a feeling of being easy to handle while allowing plenty of air. I think this is a mouthpiece that is not often available, so how about it if you are looking for one? This is a used item, so there are scratches on the shank and wiping marks. Please refrain from purchasing if you are sensitive to these details.