FastDry with 37.5 technology makes this our fastest drying garment. 37.5 technology fiber absorbs and releases sweat and is integrated into the fabric; does not wash out. Odor-resistant. 37.5 technology fiber maintains your optimal body temperature to prevent sweating. Semi-cushioned foot for added comfort. Ribbed elastic at ankle and arch supports and keeps socks from slipping. Reinforced heel and toe area for added durability. Elastane ensures the perfect fit.