Run with the expected comfort of the Smartwool PhD Run Ultra Micro 3-Pack! Sold as a three-pair pack. Micro sock sits below the ankle. Ultralight cushioning construction provides daylong comfort in close-fitting shoes. 4 Degree elite fit system utilizes two different elastics to enhance stretch and recovery. ReliaWool in high-impact areas of the foot provides long-lasting wear. 200 needle construction provides high-density cushioning without compromising its light weight feel. Achilles tab helps prevent irritation. Strategically-placed mesh vents. Nearly seamless toe. Style Number: SW000005 48 percent nylon, 48 percent wool, 4 percent elastane Machine wash warm on gentle. Tumble dry low. Made in the USA and imported.