Altus, a flute manufacturer with a factory in Azumino, Nagano, Japan, has released a ‘Ring Key Patch.’
This model uses a special sealed type made of aluminum and plastic bonded together. Compared to existing rubber types, the effect on the pitch can be kept to a minimum. It also conforms well to the shape of the key, making it possible to press down on the key naturally. Please consider this!

Altus / Ring key patch