Cymbals are a common percussion instrument. Cymbals consist of thin, normally round plates of various alloys; see cymbal making for a discussion of their manufacture. The greater majority of cymbals are of indefinite pitch, although small disc-shaped cymbals based on ancient designs sound a definite note (see: crotales). Cymbals are used in many ensembles ranging from the orchestra, percussion ensembles, jazz bands, heavy metal bands, and marching groups. Drum kits usually incorporate at least one suspended cymbal and a pair of hi-hat cymbals.