This third Next War supplement will contain the following items:

An expansion map containing the rest of Kaliningrad and a larger portion of Lithuania including the strategically important railroad connection.
Optional expansion map which depict the islands of Bornholm and Gotland as hex based maps as well as rules to integrate them into the game.
Two counter sheets containing additional and updated counters for most of the nationalities in Poland including:
New and additional ground OOB for Russia
Typhoons w/ Meteor
Additional ground units for Poland
Belgian F-35s
US F/A-18s w/ AMRAAMs
Belarus Su-30s
Additional counters for other games in the series including:
Indian S-400s
PRC DF21s/26s
Updated ROK Order of Battle for Next War: Korea (either edition)
Additional counters and Player Aid Cards for revamped Cyber Warfare rules. These new rules use the Cyber War counters from previous Supplements.
A few optional rules.
Effectively, this supplement is an upgrade kit for Next War: Poland, 1st Edition to the 2nd Edition, but, of course, it also includes goodies such as the additional counters, the ROK OoB, new Cyber Warfare rules, and assorted other optional rules.