There are 2 versions included - one in 2 flats and one in neutral. This is to help with low notes.
Expandable flute choir music:
'The concept of the expandable form gives a great deal of versatlility in any flute choir situation. This arrangement works successfully using a quartet of C flutes on the first four parts. As instruments are added they expand haromonic support, reinforce a line of another part and/or introduce new counter melodies. The intergrity of the arrangement is never compormised. It is only enhanced.'