The C# trill key is a lever activated by the first finger of the right hand to open a tone hole next to the thumb key. It simplifies many awkward trill and tremolo fingerings and has become a preferred feature among professional flutists. It is available as an option on the Azumi AZ3 flute.

C# Trill Key Fingerings:
• B to C#: Finger B and trill the C# key. This works in both the first and second octaves.
• C to C#: Finger C and trill the C# key. Again, this works in both first and second octaves.
• High F# to G#: Finger high F# and trill the C# key.
• High G to Ab: Finger high G and trill the C#key.
• High G to A: Finger high G and trill the C# trill key and the upper trill key together.
• High Ab to Bb: Finger high Ab and trill the C# trill key and both trill keys together.