The new Weightless Wool fabric is an innovative yarn with a nylon core that is wrapped in Australian Merino wool for a lightweight performance fabric that naturally out performs all-synthetic sport layers. The W2 Sport T feels soft, resists odor and performs with the versatility of wool so you can concentrate on wherever sport takes you. A nylon core is wrapped with wool to create a hardy fiber without bulk or weight. Weightless Wool is designed to be softer, more durable and lighter than synthetic workout fabrics. A perfect fabric when used alone for warmer days of aerobic work or layered to add warmth in colder activity. 145g/m2. 87% Merino, 13% Nylon.