I bought this item as a spare part for the school euphoniums, which I have the responsibility to maintain their playability as the head of brass instrument.
When I was a kid I didn't have much problem with a jammed valve due to a damaged valve guide, but my students are just mortal like the rest of the humanity, and they make mistake by forcing the valve down the valve case, while not aligning the valve guide properly with the groove.
Believe me, I have seen one kid using a hammer to try to strike the valve down... Of course it took him a little while to understand why I was yelling at him in horror...
Luckily the valve guides are made of plastic and they seldom damage the whole valve mechanism during such mishap. With a few spare parts in hand, I can make the instrument playable in just a matter of a few minutes, of course not before lecturing my student not ever, ever to do this again...
Worth noting also, that this part also works on most YAMAHA tuba, too.
