The Eastman EEP826S Professional Series Compensating Euphonium is tuned to the key of Bb with a compensating system. This professional euphonium features a .591" bore and a .610" 4th valve bore, an 11-1/2" yellow brass upright bell, stainless steel pistons and a large shank American mouthpiece receiver. Along with a silver-plated finish, the euphonium also includes a mouthpiece and protective case.