The instrument consists of a small, cylindrical shell with a top skin (or head) of calfskin, or these days a plastic material. At the opposite end to the head, underneath the shell, are some loose metal rods that look rather like springs. These can be played either loose or tightened, and it's the vibrating of these that gives the instrument its particular sound. In Western classical music the snare drum is usually played with two wooden sticks, but in jazz and popular music it forms part of the ‘kit’ and is usually hit with a single stick. In Western classical music arguably its most famous use is in Ravel’s Bolero where it maintains the rhythm underlying the work’s slow orchestral crescendo.