NANO FLEX ALL-CONDITION WARMERS Choose Nano Flex for warmers that are great in dry conditions but also give some extra protection and warmth in wet conditions. We 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. WHAT IT IS Nano Flex for the ultimate warmer: warm and comfortable in dry conditions, water repellent in damp conditions, and still warm in extreme conditions. PRODUCT FEATURES Water-repellent thermal and breathable Nano Flex fabric Flat-lock stitching with single seam Double-sided silicone grippers to keep warmers in place 12°-20°C / 54°-68°F Weight:89 g