The above two photographs show the keywork of a Haynes Silver Flute which is constructed with an open G sharp key mechanism.
On the upper photograph the G sharp lever operates directly on the key to the left and the two keys on that photograph operate entirely independently. This flute has an offset G mechanism but an open G sharp is just as easily fitted to in line G mechanisms.
The Lower Photograph illustrates the total lack of a separate G sharp tone hole.
Also can be seen the reverse B / BFlat Thumb keys which are logical but not necessarily
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The above photograph and notes are as accurate as my knowledge of the subject permits