The original gore windstopper IS waterproof. The only difference between windstopper and goretex was the fact that windstopper was the pure teflon bonded to a light nylon or polyester outer layer without sealing the seams while goretex was teflon bonded to a heavier outer layer and then protected by either a hanging mesh layer or by another layer bonded to the inside and then seamsealed. Then goretex garments had to pass their testing while windstopper didn't.