100% polyester. Nikwax windproof fabric. Full zip fastening. Drawcord hood. Ribbed cuffs. Two zippered splash pockets. Drawcord hem. Regular fit. Páramos Ostro Windproof Jacket is a thing of beauty. Dont be deceived by the lighter-than-a-bag-of-Quavers fabric – this stuff is made from that Nikwax stuff, which is fully windproof despite its ultra-light weight. Not too bad on the eyes either. Think of it like a running jacket that actually looks good.