The Arcteryx Rho Heavyweight Zip Neck can be used either as a base layer or as a mid layer, making it a superbly versatile piece for cold conditions. It is made from Polartec Power Stretch Pro, which is a very warm fleece fabric with the ability to wick moisture very quickly from the skin thanks to its brushed polyester lining. The Power Stretch is actually made of two layers, the outer being a durable Nylon that will contribute to wind resistance and will resist pilling, while the inner is soft polyester that draws the moisture away via the loose fibres. The Rho Heavyweight Zip Neck has a trim fit and the fabric benefits from a four-way stretch, so this ensures that your freedom to move is never restricted. A tall collar prevents chills and a zipped neck enables easily venting, ideal when you get too warm. A handy single zipped chest pocket, helps keep your small items safe and secure. Arcteryx Rho Heavyweight Zip Neck Features 88% Polar Power Stretch Pro polyester fabric 12% elastane Flatlock seam construction Zipped chest pocket Zip neck Single laminated and zipped chest pocket Fit:Next to skin Weight:285g Arcteryx Rho Heavyweight Zip Neck