I recently bought a brand new Ian Bousefield trombone that is very nice. I was looking through the case and found a small little drill bit looking thing. There was a copper one and a tinish looking one. There is also a perfect sized screw hole on the trombone tubing that fits these two bits. I'm not sure what they do, but if somebody could tell me that would be lovely.
They're little weights that slightly change the acoustics and response of the horn, to be adjusted to your taste. Or maybe you won't be able to tell the difference.
I don't have one so I don't know...
"I know a thing or two because I've seen a thing or two."
I have some of these with the Edwards horn that I'm playing now. While I'm not currently using them, I have tried them at the factory with the guidance of one of their trombone techs, and did find that they made a surprising difference. Not as much as changing a bell or slide, but they do adjust the sound a bit. It's a personal thing as to whether it is better or worse. Someone from Edwards/Getzen might be able to give you an idea of how to go about testing them out - what to expect. They are very helpful and know their products very well there.