Thorin's Key is the device brought along on their quest to gain entrance to Erebor, the Lonely Mountain.
This sticker is approximately 4" wide, has a glossy finish and a strong adhesive backing, and is highly durable, made from rip-proof, water resistant material. It is suitable for use on any reasonably flat surface, including walls, notebooks, windows, laptops & tablets, etc., and will not leave a residue upon removal. (It's not dishwasher-safe, will not adhere well to clothing, and is not designed to withstand harsh outdoor weather.)
