Official "early adopters version", which means you have to sign in to the ea-program to get it.
It goes live for everyone to update to in a couple of weeks, if there are no showstopper bugs discovered by early adopters.
(and sometimes the final version contains some small bugfixes to the ea-version)

Just as usual, the update is for all official devices, Jolla does a pretty good job in maintaining the old phones too.