Adds audio to a mechanical variometer or can be used stand-alone (with
a flask) to provide an audio signal. Made in Germany. I bought this
new in 1992 but never used it. Comes with all original accessories
and instructions in English. There's a photo it on the Cumulus
Soaring Classifieds website. I paid $200 for it, not sure what it's
worth now, so "Best Offer".