Accessory Expander Kits are Key Items in Xenoblade Chronicles 2. They are obtainable by trading with the Traveling Bard from Argentum Trade Guild upon New Game Plus, after finishing the game and installing Patch (Ver.1.3.0). Accessory Expander Kits increase the number of Accessory slots available to a Driver when Bonus EXP are exchanged for them. Important amount of Bonus EXP can be obtained by adding the EXP difference to the Bonus EXP pool after lowering a Driver's level at inns. Each Driver can only use an Accessory Expander Kit once.