Concertina

A concertina is a free-reed musical instrument, like the various accordions and the harmonica. It consists of expanding and contracting bellows, with buttons (or keys) usually on both ends, unlike accordion buttons, which are on the front. The concertina was developed independently in both England and Germany. The English version was invented in 1829 by Sir Charles Wheatstone, while Carl Friedrich Uhlig introduced the German version five years later, in 1834.