This is a medium large size CC/BBb tuba mouthpiece ideal for most playing situations. The Diablo is the solo counterpart to the Williwaw. The funnel cup, and slightly smaller throat creates an intense focused sound. This moderate sized mouthpiece is the perfect balance of sound projection, and ease of use. The Diablo also works well on large 6/4 F and Eb tubas, Rim is 1.28 and the throat is .318" diameter, Medium deep funnel shape cup.