US Air Force ROTC University of Missouri-Rolla Challenge CoinMeasures Approximately: 1.75 InchesNo Special EdgingFront: University of Missouri-Rolla, Stonehenge BattalionBack: Leadership, Excellence, Starts Here, Air Force ROTCChallenge Coins are generally created for the Military and are prized by the service members that receive them. Perfect for Collectors of Militaria.