Conn, French Horn, 4th Lever Spring.  See my item ID# 273180618134 for a 4 spring kit.

Fits:

MODEL & BRAND

9D Conn Double French Horn

8D Conn Double French Horn

8DR Conn Double French Horn

8DY Conn Double French Horn

9DR Conn Double French Horn

9DY Conn Double French Horn

6D Valve and Slides Conn Double French Horn