Quantum Mechanix QMx Supernatural Hunters Challenge Coin Get the Supernatural Hunters Challenge Coin! The origin of the Challenge Coin has long been debated, some think it started during World War I, others during the Second World War. The artisans at Quantum Mechanix have discovered that the Demon Hunters may have been using them for centuries to identify friend or foe while in the field. Whether they were the first to use what is now known as a Challenge Coin, this coin depicting the Devils Trap on one side and the Anti-possession Symbol on the other, may have saved the lives of many past Demon Hunters. Coin measures approximately 1 1/2-inches in diameter. Ages 13 and up.