More rugged, more weather resistant, and more breathable, WINDSTOPPER® X-FAST fabric enhances all the benefits of WINDSTOPPER® fabric and adds all-way stretch for maximum movement-mirroring ability. Totally windproof and offering virtually unlimited breathability, WINDSTOPPER® X-FAST garments provide comfort across a wide range of weather conditions and activities. WINDSTOPPER® X-FAST fabric is 100% windproof and keeps you up to 2.5 times warmer than comparable materials. WINDSTOPPER® X-FAST fabric is twice as breathable as comparable windproof products, and offers the same level of breathability as comparable non-windproof products.