Champions Of Midgard Insert: - Rules of Play says:
Insert compatible with Champions of Midgard® and The Dark Mountains® and Valhalla® expansions, as well as the viking meeples and other add-on wooden tokens. The design provides both efficient storage and improved game play. The trays can be utilised during the game, and they greatly aid set-up and clear-away times. The rules and boards act as a lid on top of the trays.