Mage Armor
Mage Armor is a property found on armor which allows for meditation in armor pieces which it would not normally be possible, such as platemail, chainmail, ringmail, studded leather and bone. A full suit of mage armor would allow meditation the same as would cloth or leather equipment, providing all set pieces have the mage armor property.
Mage armor also has no penalty on the Stealth skill.
Note that when crafting with a runic kit, it's possible to create leather armor with the mage armor property attached. However, because leather already functions as mage armor, the property does not display and is effectively "wasted".