DEG Adapts tenor mouthpiece to fit euphonium receiver Tenor to European Shank Mouthpiece Adaptor The DEG mouthpiece adaptor allows you to use a small shank mouthpiece on an instrument with a medium shank or European style mouthpiece shank The DEG mouthpiece adaptor allows you to use a small shank mouthpiece on an instrument with a medium shank or European style mouthpiece shank