Thank you for viewing. Size: Rim Diameter: 26.66mm Throat Diameter: 7.13mm Cup Depth: medium deep (between the C and E of the 3 series) This is the signature model of Joseph Alessi, principal trombone player of the New York Philharmonic. It is now discontinued and cannot be purchased new. There are marks on the shank, but they do not affect performance. In my personal opinion, the D is characterized by its deep and rich sound. Because of the large cup shape, it is very easy for bass trombone players to switch to tenor-bass trombone, or for tenor-bass trombone players to switch to bass trombone.