PhD® Outdoor Ultra Light Mini Light Gray - XL. Whether it's a trail run at dawn or a hike in the heat of summer, this multi-sport sock features the power of Merino for maximum breathability, moisture management and temperature regulation. Made with Indestructawool⢠technology for ultimate durability and the 4 Degree® elite fit system to keep the sock in place. The mini height offers the perfect balance of low profile and protection from debris.