A concertina is a bellow-driven [[instrument]]. It usually has symmetrical sides and its bellow is square, hexagonal or octagonal. Often mistakenly tagged as [[accordion]].

* Examples: 
** Square: post #1011465
** Hexagonal: post #2888534
** Octagonal: post #3114877

h4#external-links. External links

* Wikipedia article: "Concertina":[https://en.wikipedia.org/wiki/Concertina]

concertina