A combo organ, so-named and classified by popular culture due to its original intended use by small, touring jazz, pop and dance groups known as "combo bands", as well as some models having "Combo" as part of their brand or model names, is an electronic organ of the frequency divider type, generally produced between the early 1960s and the late 1970s. This type of organ predated, and contributed largely to, the development of modern synthesizers. The combo organ concept, at least in the context of mass-production, is thought to have arisen from popular demand, when smaller home organs were seen in music stores. Combo organs were probably originally developed in The United Kingdom, based on the Univox polyphonic version of the Clavioline, and some models included the inner-workings of Italian-made transistor accordions. They were the brainchild of necessity for portable organs of simple design, mainly for use in these small groups. Combo organs ended up having a major impact on the music scene of the mid- and late 1960s, particularly on rock and roll of that era.