![Nano Flex](https://www.castelli-cycling.com/medias/NANO-FLEX-BLACK.jpg?context=bWFzdGVyfGltYWdlc3wxODYyOHxpbWFnZS9qcGVnfGgzOC9oYTMvODc5NjEzNzYxOTQ4Ni9OQU5PX0ZMRVhfQkxBQ0suanBnfGU0NmMzZGJmODk2NWMxNTA4MDljNjg3ZGQ2NWEwZDE2NDFlMDY1ODk0MjRhMmVlYTAyYzI0YTViYjJlY2VkNzQ)
Exclusively engineered by Castelli. We take our thermal fleecy stretch Thermoflex fabric and coat it with millions of tiny nanofilaments to create the most water-repellent fabric finish ever. Drops of water stay as spherical balls on top of the fabric or bounce off the fabric without leaving a trace.