Choose Nano Flex for warmers that are great in dry conditions but also give some extra protection and warmth in wet conditions. Castelli invented the category of water-protective thermal fabrics, and Castelli's proprietary Nano Flex is often imitated but never equaled. No compromises for any conditions.PRODUCT FEATURESWater-repellent thermal and breathable Nano Flex fabricFlat-lock stitching with single seamDouble-sided silicone grippers to keep warmers in place8°-18°C / 46°-64°FWeight:119 g