Choroi Pentatonic flutes require regular hydration. This is a non-toxic, safe, linseed oil compound designed by Choroi to keep your pentatonic flute hydrated, inside and out, maintaining the sound quality of the instrument. May also be used on other wooden flutes and recorders. Linseed oil is also known as flaxseed oil. It is obtained from the dried, ripened seeds of the flax plant; It is a colorless to yellowish in color.