This is a BACH 3G mouthpiece for medium-large bore instruments. This is a rare item, with the shank of a large bore BACH 3G professionally modified for medium-large bore instruments. While large bore and small bore are common for instruments today, Besson euphoniums from around 50 years ago used a medium-large bore shank. Please note that this will not fit small bore or large bore instruments. There are scratches and plating peeling due to use. If you are interested, please bid. This is a home-stored item, so please refrain from bidding if you are sensitive about such things. Thank you.