I have an original one of these for french horn. While the amp/sound processing was cool, the really great thing was the air flow. It added such a minimal amo

I have an original one of these for french horn. While the amp/sound processing was cool, the really great thing was the air flow. It added such a minimal amount of resistance that you could practice in hotel rooms and avoid trips to the practice rooms in winter without totally ruining your tone or having your range affected.