Abstract: A clamp includes a flexible, interior conical component in contact with a barrel and a rigid, exterior conical component in contact with the interior component. The interior component has a longitudinal cut over its entire length and has, at the part that contacts the barrel, two central recesses. The exterior component acts on the interior component, and has the same conicity as the interior component. The exterior component prevents unwanted opening of the interior component by exerting a pressure on the interior component. Both components have a central recess, which form, as a whole, a mouthpiece resonating box that provides greater sound volume and different timbres, depending on the size of the recess and on the material from which it is produced. The flexibility of the interior component prevents breaking of the barrel even though three interior rings thereof are placed in different planes.