Waterproof Cold Weather Mid Length Sock with Hydrostop(TM) The original, mid-length Runton sock, with Hydrostop(TM). Fully waterproof and breathable, the Runton thrives in cold environments. Merino wool interior is soft and insulative, with natural odor resistance. Built for cold pursuits. Designed for cold temperatures, the Runton is insulative, waterproof, and moisture-wicking. Hydrostop(TM) reinforces waterproofness, ensuring water does not trickle down the leg into the sock. A premium merino wool interior, with terry-loop knitting, has excellent thermal properties. Merino wool absorbs moisture away from the body, ensuring breathability. An engineered nylon blend exterior has similar moisture-wicking properties, highlighting the cohesiveness of fabrics within the garment. The Runton's Aquaselaz(TM) membrane is 100% waterproof, sitting in the mid-section of the sock. Essential for cold, wet weather pursuits: hiking, trekking, mountain biking. The Runton is a relative of the Starston. - Outer Layer - 90% Nylon, 10% Elastane - Middle Layer - Aquasealz(R) waterproof membrane - Inner Layer - 35% Merino Wool, 35% Acrylic, 22% Polyester, 3.5% Nylon, 3.5% Elastane, 1% TPU