Australian Customs Service firearms officer Nigel Masterton inspects a key-ring gun and its .32 caliber cartridges in his office in Perth. The gun, which is 3 inches long and an inch wide, looks like a key ring and fires two .32 caliber bullets. The gas-fired pistol, which was designed and produced in Bulgaria, sells for about $30. U.S. aviation authorities have alerted airports and airlines and introduced new security measures in a move to detect the tiny device.