My small U.S oil company just made a 5 million dollar deal with a very poor developing country on the other side of tye world that needs oil for their economic development. Unfortunately, they can only pay me in their unstable currency called the WILD because they have no way to get U.S. dollars. My oil company tanker transportation ship will take 25 days to reach its destination on the other side of the world. If i make a deal with my global banker to buy an insurance contract to "lock in" today's favorable currency exchange rate for the next 30 days to protect me against a drop in the value of the developing country's WILD currency, then what do i call the instrument i am using?