Baubles
From ATLauncher Wiki
Baubles is a small addon mod and API that is intended to be used by other mods to add additional inventory slots to a character. It adds four new slots to the player inventory, space for an amulet, belt, and two rings.
Baubles adds only one item to the game, the Miners Ring. Its reason for being included was to serve as an example for other developers.
Thaumcraft 4 and Botania both have items that can be equipped into these slots. Extra Utilities also has Angel Ring that works in the ring slot.