ThinkGeek may have just won the competition for best Avengers: Age of Ultron licensed product -- lord knows there's enough of them -- with this ingenious Captain America Shield Backpack. It's a shield and a backpack!

Measuring 18 inches in diameter and 2.5 inches deep, it's clearly designed for kids and adults -- at least those adults who can pull off walking around with Captain America's shield strapped to their backs. The shield is plastic, rather than a vibranium-adamantium alloy (undoubtedly to keep down costs), but that should be enough to protect the contents within.

The backpack's interior features a large main pocket, a laptop/tablet pocket and and two accessory pockets. The shoulder straps are padded and adjustable. ThinkGeek offers a warning, however: "If your Avengers: Age of Ultron Captain America Shield Backpack is full of stuff (especially electronics), don't throw it like Captain America does. It won't come back to you. It will just make you sad."

The backpack is priced at $49.99, but ... it's currently out of stock (sorry). So you'll want to keep an eye on its availability, particularly if you're expecting Hydra to infiltrate your campus or workplace.