Clarinets constitute a family of musical instruments with single reeds. By far the most common is the Bb soprano clarinet, but there are instruments from many of the different members of the family on display in the Collection, including smaller 'piccolo' clarinets, alto clarinets and basset horns. Since its invention, the clarinet has developed and evolved most notably through the addition of more keys and more advanced keys. A major innovation was brought about by Iwan Müller, who in 1812 invented a new type of pad cover for the clarinet's tone holes. The new pads were completely airtight, allowing the number f keys on the instrument to be increased significantly allowing the instrument to now play in any key. The Instrument began to be made with thirteen keys and seven finger holes.