The SUSTAIN [$11.99] is the only sock on the market created from post-industrial recycled nylon. The SUSTAIN Line is Swiftwick’s finest tribute to their commitment to the planet and the earth-conscious athlete in us all. From their refusal to use chemicals to wick away moisture, to their commitment to being made in the USA – Swiftwick strives to be carbon neutral in their approach. Their philosophy is to conserve and recycle, while creating the best products you will ever wear, guaranteed. These socks have been Uber-Tested and are Uber-Awesome!