The soprillo (sopranissimo) saxophone is a straight saxophone in Bb. It is pitched an octave above the Bb soprano saxophone, and a half octave above the Eb sopranino saxophone.
It is a difficult instrument to control, and takes many weeks to keep it in tune, especially on the highest notes.
 The fingering above 'G' on top of the staff may require some modification to make the notes speak easily and in tune.
 It is useful for a sax choir(ensemble) as well as a jazz solo instrument.

See more pics on my page, and a link to the manufacturer as well.