When things heat up their 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. It's a great sock for runners who love a barely there, ultra-light feel. True Seamless construction reduces hotspots and blisters. Ultra high stitch count creates a super comfortable sock with a streamlined fit like no other. No slipping, no bunching, no blisters. Still made in Vermont. Guaranteed for life.