TubeNet

That's probably because there is a good chance that it is a euphonium. If u look at the slide set up for the valve cluster, it is very very similar. Also, the leadpipe and the bell seem way too close to be a tuba. I would ask for a bell size at least. Don't quote me on this, as I am not a certified expert.

That's a euphonium.

Yup. It's a euphonium. BTW.... I would be very concerned about the condition of the valve ports in the #1 and #3 casings. There's apparently been a pretty good 'whack' given to the 3rd valve circuit.