The BC Master flugel mouthpiece has an inside rim diameter of .625″. The rim is round on the outside edge and medium round on the inside. It has a deep flugel cup and the Legends flugel backbore. The heavyweight blank adds core and darkens the tone, creating that sought-after fluffy flugel sound. An added bonus with this model is that it has a matching trumpet mouthpiece, the BC Master. The rims are identical, allowing the player to quickly and easily transition between flugel and trumpet. The two together make a nice trumpet/flugel kit, perfect for those gigs where you want to play some intense jazz-rock and some laid back flugel jazz, too.