.425 bore horn with brass legs and nickel stockings. No leadpipe. 4" bell. No expansion in back crook and very little expansion in neckpipe. No water key. Kranz is formed to shape, then stretched onto bell without soldering, which is how it was originally done.
Kranz has blemishes where the seam was formed, and looks rather rough--or "vintage" if you choose to see it that way.
What's so great about it? It was designed to be very small in bore, unlike some reproductions which couple bell parts made for modern instruments with small-bore slide parts. It's hand made. The metal is relatively thin compared to modern instruments. And if you're into cosmetics, I think it has a much better look than modern horns with bell wires.
Pictures are posted at:
https://imgur.com/a/linR0
And here's a video of a mediocre trombone player and rather poor sackbut player with no formal training demonstrating what it sounds like:
https://www.youtube.com/watch?v=EhyioyaBujk