Leveraging the lightweight performance of Coreloft(TM) synthetic insulation, an ultralight Arato(TM) nylon shell and highly efficient ergonomic patterning, Arc teryx created an alpinist s hooded belay jacket that packs to the size of a water bottle and delivers effective warmth for a mere 290 grams. Articulated patterning and gusseted underarms provide extended mobility without sacrificing coverage. The Arc teryx Trim fit accommodates light layers, but stays close to the body for a higher level of thermal efficiency, and Arc teryx e3D (ergonomic 3-Dimensional) patterning utilizes extra space in key joint areas to bring an added level of use specific articulation. Features: Packs up small for easy travel storage Breathable Great warmth-to-weight ratio Lightweight Low profile Compressible and packable Micro-seam allowance (1.6mm) reduces bulk and weight Arc teryx Nu water repellent treatment Articulated patterning for unrestricted mobility e3D Ergonomic 3-Dimensional patterning for enhanced comfort and mobility Gusseted underarms Trim fit for base layer or light mid-layer use Insulated hood Helmet compatible No Slip Zip(TM) front zipper Full front zip with chin guard and wind flap Adjustable hem drawcord Two hand pockets with hidden zippers Included mini stuff sack with drawcord closure Stuff sack can be clipped to a harness Materials: Coreloft(TM) 80 (80g/m) insulation. Made with highly crimped multi-denier siliconized polyester yarn, this lightweight, breathable, and thermally efficient, 100% polyester staple fibre is very compressible and has excellent loft retention. Coreloft(TM) 60 (60g/m) insulation. Made with highly crimped multi-denier siliconized polyester yarn, this lightweight, breathable, and thermally efficient, 100% polyester staple fibre is very compressible and has excellent loft retention. Arato(TM) 10 - 100% nylon