Tried and true.The Mil-Spec shares specifications with U.S. Military socks, proven to promote moisture migration and support the foot's natural arch. We made a slight change to the original military design, adding a compression band in the footbed for additional performance, comfort, and arch support.After giving this sock to some hard-wearers and saying, “do your thing," the results were outstanding. This sock stood up to heavy-use hiking, trail running, biking, and other outdoor activities.