Castelli ́s Nano Flex 3G fabric is the result of a decade of development. It's their best all-around fabric for winter tights: warm, stretchy, luxuriously soft, highly breathable and on top of that it features Castelli ́s proprietary third generation of nanotechnology water-repellent finish. While other companies are using simple chemical water-repellent finishes, Castelli create a nanotechnology mechanical repellency to enhance a chemical DWR finish. You stay drier and more comfortable. Even though this tight features Castelli ́s latest water-repellency technology, don't think of it as just a niche rain tight. The fabric makes for a great dry-weather tight, and the reduced-seam anatomical cut makes it extremely comfortable. They use the pro-level KISS Air2 seat pad along with a mesh bib and zippered ankles. This is the tight that's good at everything.