The Conn Wonder has an interesting feature. Note the small devices on the tuning slide. They allow pushing the slide in with the left thumb and pushing it out with one of the fingers using a normal left hand grip. Should you want to adjust tuning on the fly, it is quite easy.
Also, I haven't measured the bore size, but it certainly feels like a small bore. Very easy to play from low to high with a consistent tone.
Anybody know more about this cornet?