We always strive for total performance & total innovation but sometimes we surprise ourselves. This Nano Flex fabric behaves just like our Thermoflex fabric in dry conditions but then provides unbelievable water repellency when it starts raining. We dont claim that its fully waterproof but its the most effective thing weve ever made for keeping you comfortable in all conditions. Its just barely short of a miracle. Water-resistant Nano Flex fabric. Same breathability stretch & warmth as our standard Thermoflex warmers. Great in every possible condition. Cam-Lock zip to aid fitting. 134g (pair)