Fit & Design: Slim fit bottoms Regular rise - Sits below the natural waist The low-profile elastic waist and leg openings offer a great fit Low-profile side seams maximize comfort Features super-soft, stretchy, and durable Corespun merino wool jersey fabric Technology: Merino Corespun - durable merino blend regulates body temperature in all weather conditions Ultralight 150gm Corespun fabric features merino fibers wrapped around a nylon core, for underwear that is durable and soft next to your skin Additional Details: icebreaker harnesses the performance qualities of natural fibers to offer an alternative to clothing based on petrochemical synthetics Merino is an annually renewable fiber that naturally resists odors, keeps you cool when it's hot and warm when it's not, and lets your skin breathe for comfort all day, every day