The natural horn, like the natural trumpet, is a brass instrument with no valves. The notes available are the notes of the harmonic series which is dependent on the length of the instrument. A series of coiled crooks are used to change the length and therefore the key of the overall instrument. Unlike the natural trumpet, the natural horn is able to augment the notes of the harmonic series by use of the right hand in the bell of the instrument, using a technique known as hand stopping.