The Armor GUI is a new tab found in the inventory that is added by Tinkers' Construct. This GUI allows for certain additional equipment to be added. It has currently only two purposes: heart canisters and backpacks. Heart canisters are added to the trinket slot in the bottom right.
Update 1.3.5 to Tinkers' Construct included knapsacks, which can be equipped in the appropriate slot. When equipped, a new tab shows up on the GUI which opens a secondary inventory within the knapsack, similar to the backpacks crafted in the Backpacks mod. It cannot be opened without going through the inventory screen, unlike the backpacks from the Backpack mod when they're equipped.
- Item #6282 (currently untitled) is the exact shape as the bottom left slot, and when it is placed in its corresponding slot, Hexxit will crash.
- Currently only the KnapSack and the Heart Container can be used with a purpose, all the other slots do nothing.
- The GUI still has bugs, such as the ability to put any item into the new item slots. This essentially gives the player seven additional slots to your inventory.
- If you equip item #6282 to the same-looking slot the game will crash.