Windproof in which direction?
I gather the original issue were Pertex and made by Snugpak. Later issue were copied by another company with a thinner ripstop Nylon outer, basically thin light Pertex. They are certainly wind resistant but if you want windproof then go for Goretex. These are best used for static work and sleeping, not for yomping and working up a sweat in. They aren't hard wearing. I'm about to buy a pair for staying warm whilst chilling
around a Winter camp fire and kipping in my underquilted hammock. Watch out, they are very generous in size, you probably need a size down from what you would normally choose. Also, they are designed to be easily worn over your clothing so they loft fully (rather than being compressed by outer clothing) and can easily be removed when not needed.