Thumbport 

The Thumbport aids the balance in holding the flute, which is comprised of a C-shaped shell and an extension from one end of the openings. This thumb-like extension is toward the flute player when the C-shell is clamped onto the flute. The Thumbport guides the player's right thumb at an efficient location and provides additional support.

Because nine of our fingers are used to operate keys on a flute, only one, the right thumb, is left to decisively balance it. Many flutists knowingly or unknowingly use their right little finger to help. It reduces the agility of not only the little finger but also the rest of the right hand. The Thumbport snaps onto to the flute at around the F key. It guides one's right thumb to support the flute at an angle. This force can be seen as the sum of two separate branches: one supports the flute from below and the other counters the horizontal rotation. The extension arm rests on the thumb gently, which easily prevents the flute from rolling.

What is the difference between a Thumbport and a Thumbport II? click here