This mouthpiece has the same rim contour of the deeper B1-1 S1 and B1-1 S5, but with a cup depth that is between the conventional C and D cup depths.  Many players who use the B1-1 S1 or B1-1 S5 for all around playing like the B1-1LD S1 when they need a brighter sound and easier upper register for lead or commercial playing.  It is not a particularly shallow mouthpiece, and is deep enough that most player do not have issues with bottoming out.  Some classical and orchestral players who either have a very dark natural sound or who like to play with a slightly brighter sound all the time use the B1-1LD S1 as their main mouthpiece.