Smartwool Hike Full Cushion Crew socks, formerly PhD® Outdoor, use cushioning on the entire sock to help maximize warmth and protection. These responsibly sourced, ZQ-certified Merino wool hike socks are built with top sock tech, including Indestructawool™ technology for enhanced durability, 4 Degree™ Elite Fit System for a dialed-in, performance-oriented fit, and Virtually Seamless™ toe for maximum in-shoe/boot comfort. Smartwool have updated their hike line by improving mesh zones for additional breathability, as well as creating a new ply structure that reduces pilling while enhancing hand-feel and comfort. These hiking socks are now made with recycled nylon, making them more sustainable than ever. Now that's something you can feel good in and about.