Darn Tough’s Pennant RFL Over-the-Calf Ultra-Lightweight sock provides the most secure and dialed connection between your feet and touring boots for unparalleled comfort on the skin track. The Merino wool construction naturally regulates your foot’s temperature and stays warm when wet so you can venture into the backcountry with confidence. The Ultra-thin, performance fit also offers next-to-skin comfort for long days on the skin track.