Mine Countermeasures Squadron (MCMRON) 7. Condition: Used, but in good condition. The coin is 3 x 3 1/4 inches. NOTE: Never personally given any of the coins. All coins are guaranteed to be in excellent condition unless specified above. The free listing tool. The item “Mine Countermeasures Squadron (MCMRON) 7 Chief’s Navy Challenge Coin” is in sale since Wednesday, February 17, 2016. This item is in the category “Collectibles\Militaria\Current Militaria (2001-Now)\Original Items\Challenge Coins”. The seller is “rolyat11″ and is located in Panama City, Florida. This item can be shipped worldwide.