Free reeds are the larger category of musical instruments that the accordion and concertina belong to. There are many reed instruments in the world, but most of them are not free reeds. The saxophone and clarinet are examples of instruments that work with reeds, but they are not considered free reeds because the reed is part of the mouthpiece, and the tone is controlled by the player. Free reed instruments have reeds that produce a single tone when air is passed over them.