The Holton TR181 Professional Independent Double Rotor Bass Trombone has been a standard of professional players for many years. The TR181 features a .562 bore with an inline independent double rotor system in the key of Bb / F / Gb / D / G / Eb. The TR181 also features a 10 Rose brass bell for outstanding resonance and projection. The Holton TR181 Professional Independent Double Rotor Bass Trombone inlcudes a case and mouthpiece and is available in lacquer finish.