For years, how to hold and balance a flute has been much debated.
The Thumbport is made of non-scratching hard rubber and fits under the right thumb on the flute for improved position and balance.
The thumb port is designed to help relieve the strain and stress of playing the instrument. Simply clip it onto the flute tube around the F key, ultilizing the only finger that does not operate any key - the right thumb, it provides more freedom and the potential to correct the awkward holding of the flute.
The Thumbport II has a lower default angle for the thumb. It’s a little thicker and more rigid. It touches the flute tube less. And, its extension arm is a little shorter (when attached to the flute, it may go into the case easier for some). Also, the end of the extension has a more rounded shape.