This instrument is pitched an octave below the Bass Recorder. It is rarer than the Great Bass, and like the Great Bass it is not available in an inexpensive plastic form. That said, they are valuable instruments in the recorder consort and can make fine additions to any wind group. The sound of these instruments is very akin to that of diapason pipes on a grand Pipe Organ. Their sound is very breathy. Despite their name, these instruments are not as low as you would think.
Most Contrabass Recorders can only be played standing up.
A demonstration of a Contrabass Recorder (note, instrument is pitched at A=415)