High quality large shank trombone mouthpiece by Bach. Large shank mouthpieces fit in what are sometimes called symphony tenors - horns with a 0.547" bore like the Bach 42. These are common in the band world, and the most common size among orchestral players. Some jazzers use a big horn too but not many. Bass bones, 0.56" bore like a Bach 50, accept large shank mouthpieces as well. If your trombone takes a large shank piece, this one's for you.
6-1/2AL / Medium deep / 25.40 mm / Medium wide, well rounded. / 0.261" "G" / 420 / The same cup, throat, and backbore as No.612AL small shank tenor trombone but with bass shank. It requires a well developed embouchure.