Light enough to be a first layer. Warm enough to be outerwear when active. And smart: moisture-wicking, quick-drying. The Bat Hang's dual fabrics are pieced for max efficiency and comfort. Brushed for softness. (We don't mind harsh environments. But we don't tolerate harsh textures.) According to First Ascent Guide, Chad Peele, "I've heard stories of guides showering in this so as not to take it off." Enough said. Machine wash. "Looks technical...that's because it is. Why shouldn't a light outer or base layer have as much thought put into it as a shell jacket?" - Seth Waterfall "An essential piece of cold weather protection for me. High breathability, excellent wicking, form fitting and a sweet hood makes this my number one go to piece. First piece on, last one off, every time!" - Chad Peele