For those who want the lightest running sock but still want a Super-fine Merino wool, the Ultra-light fits the bill. Nothing but protection between you and your running shoes. FEATURES: -Our patented Full Contact Fit ® hugs the contours of your foot and stays put so there are no loose socks to rub you the wrong way. This no-show sock will not fall down into your shoe. -Flat knit design for zero bulk. -Fully vented top for maximum breathability. -No show height. -No cushioning in the footbed. MATERIALS:-Super-fine Merino Wool 66%-Nylon 27%-Polyester 5%-Lycra 2%