Item from The Lord of the Rings by J.R.R. Tolkien
A shirt of mithril rings — light as a feather, hard as dragon-scales, worth more than the entire Shire, given by Bilbo to Frodo as the most practical gift in hobbit history.
The mithril coat is the kind of gift that saves your life and then haunts your accountant. Bilbo received it from Thorin in Erebor, wore it under his waistcoat for decades without anyone knowing, and passed it to Frodo as casually as one might hand down a pocket watch. Gimli later estimated its value as greater than the worth of the entire Shire, and no one contradicted him. In practical terms, the coat has stopped a cave-troll's spear thrust and an orc's blade — blows that would have been instantly lethal to the small Hobbit wearing it. The mithril does not just resist penetration; it distributes force across its entire surface, turning killing blows into bruises. The psychological comfort of wearing it is almost as valuable as the physical protection — knowing you are wearing the finest armor ever crafted by Dwarven hands allows a certain recklessness that Hobbits in mortal danger occasionally need.
A shirt of small, interlocking rings made of mithril — the rarest and most precious metal in Middle-earth. The rings are so finely wrought they feel like silk against the skin. The metal gleams with a cool silver-white light, brighter than polished steel. It weighs almost nothing despite being a full shirt of mail. When worn under clothing, it is invisible — no bulge, no sound, no weight to betray its presence.
Also known as: the mithril coat, mithril shirt, mithril mail, Bilbo's mail-coat