D'addario Reserve Bb Clarinet MouthpieceMilled from solid rubber for the ultimate in consistency and tonal beauty, Reserve was created to simplify the all around playing experience for students and professionals. The Mouthpiece Test Response When testing mouthpieces, personally or with students, you should first listen for a comfortable, free response. Play a slow scale or passage, both slurred and articulated. Is the sound produced easily? Is it possible to slur and articulate clearly,