Darn Tough Coolmax Vertex Quarter Crew Ultralight Socks - Women's White Medium 41% polyester When things heat up Darn Tough's Vertex 1/4 sock made with Coolmax stays cool Coolmax Polyester yarns are engineered to move moisture away from your skin and be fast drying. Its a great sock for runners who love a barely there, ultra-light feel True seamless contrstruction provides a smooth performance fit and assures there's no slipping, bunching, or blisters Still made in Vermont, USA. Still unconditionally guaranteed for life.