Nano Flex Warmers are distinguished by their extremely versatile range of applications. They provide warmth like traditional warmers, but are primarily a decent moisture barrier in the rain. As the first manufacturer, they have utilized water-repellent thermal materials for cycling clothing. Many have attempted to imitate Castelli's Nano Flex – always without success. Uncompromising in all conditions. The water-repellent, warming, and breathable Nano Flex material ensures a flat seam. Silicone grippers on the inside and outside guarantee a good fit.