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Mountain Equipment says:
A hybrid, highly breathable mid-layer for fast moving alpinists and ski-mountaineers.
With super fast drying POLARTEC® Alpha® insulation, this is the perfect midlayer for moving quickly in cold conditions. Zoned Pontetorto® Tecnostretch fleece ensures an athletic fit and even greater moisture transfer as well as adding stretch to the hood which works with or without a helmet.