Timbales or pailas are shallow single-headed drums with metal casing. They are shallower than single-headed tom-toms, and usually tuned much higher. The player (called a timbalero) uses a variety of stick strokes, rim shots, and rolls to produce a wide range of percussive expression during solos and at transitional sections of music, and usually plays the shells of the drum or auxiliary percussion such as a cowbell or cymbal to keep time in other parts of the song.