Backun Clarinet Bell, MBGSF, Grenadilla, Traditional, Flat, without Voicing Groove Backun Grenadilla Clarinet Bell For Bb / A Clarinets Traditional, Flat, Selmer Style without Voicing Groove Model MBGSF (Diameter 26.45mm, Depth 21.65mm) The most afforable way to improve your clarinet's tone and response. Used by professionals throughout the world.