This is a tool I use frequently with my brass pupils when I'm teaching about the harmonic series and natural brass instruments! A lot of people stick a funnel in the end to make it look more like a real instrument, but that's optional! Mine is clear tubing my mother got me from the hospital... I don't care to know what it was used for; most people however, use a plain old garden hose!
Abusive comment hidden.
(Show it anyway.)