F. A. Reynolds 3P front action bell front BBb tuba - spring mechanism on the 1st valve slide

1. Female bell collar

2. Bell flare

3. Valve buttons view

4. Bell stack view

5. Ferrule view

6. Water key

7. Male bell collar

8. Thumb ring

9. Valve section back view

10. 1st slide spring

11. Leadpipe view

12. Two big sections