Domo Wiki

Dimensional pocket is storage space that can be obtained through the Housing system. Initially it can only be accessed from inside the player's residence. If you have 200 or more furniture slots, not pieces in your residence, access to the Dimensional pocket is available outside the residence, via your inventory, right next to the open wardrobe button/icon.

Dimensional pocket size depends the number of floors your residence possesses. You can obtain 5 slots per floor, for a total of 25 slots. Dimensional pocket size can be increased up to 325 slots by purchasing Item Vault Expansion Scrolls from the House Items tab in the Item mall.

The pet menu is where you see the option to store pets in the item vault. This works like a hibernation box in that pets stored will not lose loyalty. This can be used to rearrange pet order as well.

The item vault can store basically whatever goes into a bank. Including stacks of items, onyxes, slayer/flyer quest scrolls (though it will not display the quest or progress), modded costumes, armor, weapons, etc.