A heavyweight woven that's been brushed for softness. It's thicker than your average flannel, so you can wear it over a shirt (hence the name) or by itself. New fabric alert: this heavier cotton fabric is woven then sheared which makes it feel almost like suede. Except it’s way softer and warmer, more durable, and wind resistant. Take that, suede Colin is 6'1", wears a Medium, and in case you were jealous about how nice he looks in our tees....just know he puts them on in a really weird way. Sorry Colin, you know it's true.