The contrabassoon, also known as the double bassoon, is a larger version of the bassoon, sounding an octave lower. Its technique is similar to its smaller cousin, with a few notable differences.

The instrument is twice as long as the bassoon, curves around on itself twice, and, due to its weight and shape, is supported by an endpin rather than a seat strap. Additional support is sometimes given by a strap around the player's neck. A wider hand position is also required, as the primary finger keys are widely spaced. The contrabassoon has a water key to expel condensation and a tuning slide for gross pitch adjustments. The instrument comes in a few pieces (plus bocal); some models cannot be disassembled without a screwdriver. Sometimes, however, the bell can be detached, and instruments with a low A extension often come in two parts.

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