The correct answer is A) has outside threads on both ends. A double male coupling is a type of pipe fitting that has outside threads on both ends, allowing it to connect two male threaded fittings together. This design allows for a secure, watertight connection between two male-threaded components, which is important in maritime applications where the Coast Guard may encounter this type of fitting. The other answer choices are incorrect because: B) taking two men to operate is not a defining characteristic of a double male coupling, C) a double male coupling does not have inside threads on both ends, and D) a double male coupling does not have a left-hand twist.