Warm Weather Is Never A Constant, Even In Summer. Superlight And Packable – It Stuffs Into Its Chest Pocket – The Atom Sl Anorak Hits That Zone Where Insulation Is Required, But In An Amount That Suits Milder Conditions. Strategically Placed At The Chest And Back, The Coreloft™ Insulation Is Efficient, Light, And Compressible. The Tyono™ 20 Outer Balances Airflow With Wind Resistance, A Dwr Finish Repels Moisture, Stretch Fleece Side Panels Ventilate, And An Uninsulated Hood Adds Coverage.