Vapor Air is a sail designed specifically for foil racing.

GA designed Peter Munzinger: "Basically at a high level you are not competitive anymore without a specific foil sail. In general the foil sails are more high aspect, more closed in the leech as the sailing on a foil is very different than on a slalom board, just think of the missing hitting of the chop, it is much smoother. And the courses are very different, here we are talking about upwind races."

Technical details: https://ga-windsurfing.com/sails/vapor-air/