Some of our best riding takes place in winter when the air is fresh and crisp. Winter riding can be spiritual, however, at times, we ride when its downright frigid. The Thermeator is designed to help keep your feet dry and warm during the longest days in the saddle. It starts with THERMOLITER, a special hollow core performance fiber that provides warmth without adding extra weight. Thermeator is 30% lighter in weight compared to a similar knit sock constructed of Merino Wool. It also has a faster drying rate. The Thermeator quickly wicks moisture away from skin and is lightweight for less bulk inside your shoe. The Thermeator is flexible and thrives in cold, damp climates. Soft hollow fibers full cushion sole yields extra warmth without weight. Sizing: Small Women 6 8 Medium Men 7 9 Women 8.5 10.5 Large Men 9.5 11.5 Women 11 13 Extra Large Men 12.