Английский словарь американских идиом - sell snow to the eskimos

{v. phr.} To sell something to people who already have a large quantity of the same or similar goods. * /My Alaskan friend said, "One of the hottest businesses in Alaska is refrigeration. You could say that I, as a refrigerator expert, am selling snow to the Eskimos."/ See: CARRY COALS TO NEWCASTLE.