stylistic:style_transfer, structural:reformatting
Valve attachments

Modern trombones often have a valve attachment, an extra loop of tubing attached to the bell section and engaged by a valve operated by the left hand by means of a lever or trigger. The valve attachment aids in increasing the lower range of the instrument, while also allowing alternate slide positions for difficult music passages. A valve can also make trills easier.

The valve attachment was originally developed by German instrument maker Christian Friedrich Sattler in the late 1830s for the Tenorbaßposaune (lit. ' tenor-bass trombone '), a B♭ tenor trombone built with the wider bore and larger bell of a bass trombone that Sattler had earlier invented in 1821. Sattler's valve attachment added about 3 feet (0.9 m) of tubing to lower the fundamental pitch from B♭ to F, controlled by a rotary valve, and is essentially unchanged in modern instruments.

Valve attachments are most commonly found on tenor and bass trombones, but they can appear on sizes from soprano to contrabass.