Emanuel Hüller (of Graslitz in Bohemia) BBb helicon 3RV with the half-step interval placed in the 1st valve

1. Valve section view

2. Side view

3. Large bow view

4. Bell view

5. Bell flare

6. Bell view #2

7. Front view

8. Bell engraving

9. Leadpipe view

10. Body back view

11. Bell view #3