The term Squeezebox (also Squeeze box, Squeeze-box) is a colloquial expression referring to any musical instrument of the general class of han-held bellows-driven free reed aerophones such as the accordion or concertina, including the harmonium, a small, portable, hand held instrument that is quite often used in South Asian and Middle Eastern music. The term is so applied because such instruments are generally in the shape of a rectangular prism or box, and the bellows is operated by squeezing.