Hall Flutes makes "crystal" flutes of Pyrex glass.
This is a neat instrument...it is a quite lovely, visually striking flute.
This is not a particularly easy flute to play, I think mainly because of the unique "raised lip" embouchure hole construction, but once you get used to it, it does play, and has a roughly two-and-a-half octave diatonic range.
This flute cannot be pushed very hard, and plays with a soft tone and a moderate volume.
While not a useful instrument for sessions, it is a fun way to get a playable flute at home for under $100. Also, the volume is soft enough that it won't be offensive to family or neighbors.
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