The Bach 42BO Stradivarius Series F-Attachment Trombone is a best seller and the ideal instrument for both advanced students and professional trombonists. An open wrap design results in fewer bends in the tubing, which creates a free-blowing trombone. The 42BO with a .547-inch bore and 8.5-inch bell produces a large, symphonic sound with clear projection. Included with this Bach Stradivarius F-Attachment Trombone is a case and mouthpiece. The 42BO Series features an open wrap F attachment section. The open wrap offers a more uniform sound, so when the trombone player uses the F attachment the sound is not different from the sound of the trombone without engaging the trigger. Bach Stradivarius trombones are famous for their fullness of sound and projection. This is achieved by use of one-piece construction, allowing for unrestricted vibration of the bell. In addition to the shape of the bell flare, the type and thickness of the bell material also affect the sound. Gold brass, which is softer with a red tint-due to a higher copper content-results in a warm tone. Silver plated bells create a full complement of partials, or overtones, in the tonal spectrum for a focused sound with great projection. Trombones with a heavyweight bell in yellow or gold brass can be special ordered for a player needing an instrument for situation involving dark qualities or high dynamic levels without distortion. Lightweight handslides, denoted by LT before the model number, indicates a handslide made of nickel silver. The weight of the slide has been reduced by using nickel silver tubing on the outer slide tubes. Lightweight slides offer a quicker response than traditional yellow brass slides, and are also more resistant to corrosion.