Aquabloc IX mittens are made waterproof with an Aquabloc insert. Aquabloc is Gordini's proprietary waterproof breathable windproof technology. Exclusively engineered for handwear, this is an insert technology that allows moisture accumulated from within the mitten to escape and provide breathability and enhanced warmth and comfort. The molecules of the insert are wide enough apart to allow moisture to escape, yet close enough together to guarantee that water will not penetrate the mitten.