Warm breathable Leg warmers with Castelli’s advanced Nano silicone treatment for fantastic water resistance. Nano Flex fabric behaves just like Thermoflex fabric in dry conditions, but provides unbelievable water repellency when it starts to rain.More Flex, More NanoNano Flex leg warmers have been in Castelli’s collection for seven years, and they have now found a way to improve them! Introducing Nano Flex+ Leg Warmers with an added insert on the back in Nano Light fabric to help them bend around your knee whilst not compromising on water protection. They are even more comfortable than before due to more flexibility. With an added insert on the back in Nano Light fabric to help them bend around your knee whilst not compromising on water protection. Nano Flex FabricExclusively engineered by Castelli, NanoFlex consists of Thermoflex fabric with millions of tiny silicone nanofilaments on the surface to create the most water-repellent finish ever. In wet conditions, water droplets simply bounce off the fabric without leaving a trace. The silicone nanofilaments also trap a layer of air between them for excellent insulation and prevent water from soaking through to the fabric underneath. In dry conditions, Nanoflex provides the same warmth and feel of regular thermoflex fabric. NanoFlex is not completely waterproof but maintains full stretch, breathability and freedom of movement for weatherproof protection with un-compromised performance in all conditions.