Brass Lab. Momo (formerly Atelier Momo) Euphonium Thick-Rim Mouthpiece This is a handmade mouthpiece exclusively sold by Low Brass Center. It is a model that has been brushed up in terms of blowing feel based on the Yamaha 51D. The specifications are also similar to the Bowman model. It is also recommended for trombone players who prefer a deep U-cup.