The split E mechanism is designed to make the high E more responsive. This mechanism physically splits the double G keys. When playing G, the keys behave as normal, closing both of the G keys.
When fingering high E, the mechanism closes the lower of the two G keys. This creates ideal venting for this note and therefore makes this usually troublesome note very stable. The high E speaks easier, and slurs from high A to E are much easier. The split E mechanism is only available with offset G keys. It is available as an option on Azumi flutes.