Smartwool's Hike Full Cushion Crew socks, formerly known as PhD Outdoor, feature cushioning on the entire sock to help maximize warmth and protection. These responsibly sourced, ZQ-certified merino wool hike socks are built with Smartoool innovations, like Indestructawool technology for enhanced durability, 4 Degree Elite Fit System for a performance-oriented fit, and Virtually Seamless toes for maximum comfort. Smartwool updated their hike line by improving mesh zones for additional breathability. And, Smartwool's best-feeling, best-fitting hiking socks are now made with recycled nylon, so they're more sustainable than ever. Additional body-mapped mesh zones for added breathability Summer 2023 product Equipped With Indestructawool Indestructawool technology features a patent-pending construction method for exceptional durability and comfort. 4 Degree Elite Fit System 4 Degree Elite Fit System uses two elastics for greater stretch and recovery properties that keep the sock in place so you won’t get any bunching. Virtually Seamless Toe The Virtually Seamless Toe is knit to minimize blisters, hot spots, and in-shoe discomforts while you cycle, run, and hike.