Filled with tiny, insulating Primaloft fibers that weigh less than a hair but warm better than the thickest of wool hats. The Nano vest weighs in at 7oz and warms better than any synthetic insulation. Windproof, water-resistant. 100% recycled poly shell with 60g Primaloft Gold insulation. Catalog/web only. XS(2), S(4-6), M(8-10), L(12-14), XL(16).