Connection from low-G-key to close high-G-vent

Use:
C#-above-middle-C can be fingered: c# ● ● ● / ● ○ ● F for lower pitch and better legato with B-below-middle-C (compared with c# ● ● ● / ○ ● ● F).

Notes:
This connection is usually found on bassoons with the high-G#-ring mechanism.