The 42BO Series features an open wrap F Attachment section. The open wrap design of the rotor section places fewer and larger bends in the tubing, resulting in less blowing resistance. The open warp also offers a more true sound, so when the player uses the F Attachment the sound is not different from the sound of the trombone without the trigger engaged. Bach Stradivarius trombones are famous for their fullness of sound and projection. This is achieved by the use of one-piece construction, allowing for unrestricted vibration of the bell. In addition to the shape of the bell flare and the type and thickness of the bell material also affect the sound. Gold brass, softer and more red than the standard yellow brass due to a higher copper content results in a warm tone. Sterling Plus bells create a full compliment 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. The lightweight slide offers a quicker response to the player, while being resistant to corrosion.