Insulation reduces heat loss and increases warmth, even in the coldest temperatures Lightweight construction gives comfort and greater mobility Elastic binding at collar, cuffs and hem As fleeces go, the Glacier is a classic. This zip-up version is made from Polartec micro fleece that delivers lightweight warmth thanks to its unique lofted structure. Air pockets trap air without compromising breathability, so you stay warm without getting sweaty. It's the ideal layering piece to wear with a breathable-waterproof shell.