Backun Clarinet Bell, MBCS, Cocobolo, Traditional, without Voicing Groove Backun Cocobolo Clarinet Bell For Bb / A Clarinets Traditional, Selmer Style without Voicing Groove Model MBCS (diameter 25.70mm, depth 20.20mm) The most afforable way to improve your clarinet's tone and response. Used by professionals throughout the world.