What is it?
From the Dictionary.com, “Bellows” ischamber that to expel
This can either single or a pair of a device which is purposely constructed to furnish a strong blast of air. In simple terms, bellows is made of a flexible leather airbag that is capable of producing and directing a certain amount of air through a specific passage. This airtight flexible leather produces air by compressing and relaxing the sides.
A good example is an accordion that produces sound by compressing and relaxing of the air bags. The accordionist plays the instrument by swinging both sides whereby the air produced blows and vibrates the internal sound plates.
SOME IMAGES OF BELLOWS