The Smartwool PhD Outdoor Medium Crew Socks are SmartWool's best hiking, trekking outdoor sock. Searching for a versatile wool sock that has it all? Look no further:The PhD® Outdoor Medium Crew offers fit, comfort, and durability wrapped together in one smart sock. These performance hiking socks feature Indestructawool™ technology for ultimate durability, our 4 Degree™ elite fit system for a dialed fit, and our signature Virtually Seamless™ toe for extraordinary comfort in any trail shoe. With medium cushioning to help provide impact protection and ultimate comfort on the trail, this Merino wool hiking sock can handle any hike or outdoor activity.