In Prodigy, there is an equippable item called a ring. Its slot can be found if you click on yourself outside of battle, and click out of the "show stats" or "key items" option. Go to "see gear" option and click on the empty slot that later says, "Pick a ring". There are currently no rings in Prodigy anymore due to the misplacement of Barnacle Cove. Rings are classified as under a different item category.