From their website:
The war is heating up in Westeros, and additional support is needed to ensure your house remains a contender in the game of thrones. As the battles become more frequent, new banners would go a long way in raising your army’s morale and establishing a notable presence on the battlefield.
Fantasy Flight Games is pleased to announced Premium Banner Packs for Battles of Westeros. These customizable packs of sturdy plastic banners, which replace the banners included in the Battles of Westeros Core Set, come complete with enough material to completely enhance your House Stark and House Lannister forces.
Each pack features 44 plastic banners with accompanying sticker sheets that coincide with the green, blue, and red banners for both Stark and Lannister. These banners are designed to enhance your Battles of Westeros experience while also allowing players to supplement their Core Set material with additional banners of your own choosing. These new banner packs are also great for players looking to create their own scenarios.