Merino wool is a natural fiber grown by Merino sheep. It's thinner and softer than regular wool-making it easy to wear next to the skin and when you wear wool next to the skin, a lot of benefits come with it. The snug fit encourages proper blood flow Prevents from causing blood clotting Supports lower leg to alleviate tension Helps relieve symptoms caused by varicose veins, skin ulcers, and deep vein thrombosis Designed to reduce ankle and foot swelling Wicks away moisture UPF Protection (UPF 30+) Materials: 32% Marino Wool, 31% Bamboo Rayon, 32% Stretch Nylon, 5% Spandex Moderate Compression: 15-20mmHg Sizing Small/Medium: Men’s 6-9 and Women’s 5-10 Large/XL: Men’s 9-12 and Women’s 10-12