This Smartwool PhD Outdoor Medium Crew 3-Pack of socks are engineered with hard work and dedication in mind. Crew socks that sit at the calf. Sold as one-pair pack. The PhD socks are packed with technologies that are designed to keep your feet comfy so you can focus more on the trail. 4-Degree Elite Fit System construction uses two elastics to provide better stretch and to keep your sock in place. Medium cushioning that balances warmth and protection in colder weather. ReliaWool technology provides added durability in high impact areas. Mesh panels on the out step help provide added breathability. Flat toe seam is designed to prevent chafing. Style Number: SW000558 63 percent Merino wool, 35 percent nylon, 2 percent elastane. Machine wash, tumble dry. Made in the USA.