Specifically, the new Kit Kats feature a mint creme top half joined by a dark chocolate bottom half. It's a little bit of a different take on the Mint Chocolate variety they occasionally put out for the Christmas season.
Kit Kat Duos Mint and Dark Chocolate are set to arrive nationally starting December 2019 as a permanent addition to the line up (the first in almost a decade).
It appears that the brand intends to release other Duos flavors at some point.
Photo via Kit Kat.