This is a Sachs Huret DuoPar (dual parallelogram) rear derailleur. This is a very rare product and is very hard to find. This particular model is made of titanium, as opposed to later models, that were made of steel. It was manufactured as a touring derailleur, and thus is a long-cage derailleur.
This is a used product and is sold as-is. Photo is representative. We do our best to represent products accurately, but be aware that the actual product condition may differ.
Feel free to contact us with any questions or inquiries!