The trombone is a large brass wind instrument with straight tubing in three sections, ending in a bell over the player’s left shoulder.  A unique feature of the trombone is the slide. While other brass instruments change pitch by pressing valves to change the length of the air flow, the trombone player simply moves the slide in and out to change the length of the instrument. Trombones can be found in wind ensembles, concert bands, symphony orchestras and marching bands, as well as trombone trios, quartets, and choirs. The size of a trombone choir can vary greatly from five or six to twenty or more members.