Enchanted Robe of the Mage (3.5e Equipment)
From D&D Wiki
The Enchanted Robe of the Mage is essentially an Adamantine Robe of the Mage that has had its properties magically exaggerated. While it still weighs but 5 pounds, it grants a base armor bonus +8, DR of 3/-, and has hardness 15 and 30 hit points. This augmentation costs as a +3 enhancement bonus (unlike most magical armors, this does not require a +1 or better enhancement bonus), and the robe may only be improved as a magic armor.
To craft this augmentation into an Adamantine Robe of the Mage, it requires a caster level of 9 (or higher, if the robe already has an enhancement bonus or effective enhancement bonus), Mage Armor, Craft Magical Arms & Armor, Craft Wondrous Item, and the GP and XP costs to enchant the robe (if the robe does not already possess an enhancement bonus or effective bonus, these costs are 4,500 gp and 360 XP). The improvement requires 9 days to enchant into the robe.
Unlike traditional magical improvements, this augmentation continues to function normally within antimagic effects and on planes where magic functions differently, as it is a magical exaggeration and not an enhancement in the traditional sense. At the DM's option, certain deity- or epic-level effects may negate this immunity. The augmentation is quite popular amongst high-level rouges and bards (who typically have the tunic version) and war wizards (who wear the more traditional/common robe version).