The amulet of vis storage is a peculiar object worn in the baubles menu. It can store 250 vis (of each aspect) at a time, and while worn, it will supply vis for any active Repair enchantments or Runic Shielding. Also, if you are wielding a wand, staff, or scepter, it will slowly (1 CV/tick) be recharged using the vis in the amulet. Unfortunately it can only be recharged using a Wand Recharge Pedestal, or (slowly) using vis relays.
There is also an uncraftable "trinket" version called the Vis Stone, which acts similarly but has only a tenth of the storage capacity (25 per aspect). It can be found in dungeon chests.
Middle Item: Mundane Amulet.
2x Primal Charm.