The Arc’teryx Atom SL Hoody men’s hooded insulated jacket can be worn as an intermediate insulation layer in fair weather or as a layering piece in cold conditions. Lightweight and highly compressible, it stores and carries easily for your city outings as well as faraway trips. Layering is the key of keeping you dry, warm and using your energy efficiently. Put into the right systems, a good sequence of layers moves moisture away from your skin, conserves or dissipates heat and provides you with weather protection. Here they are. The first layer, worn next-to-skin will provide warmth and quickly move moisture away from your skin. Then, the second layer, is the insulation and fleece, that provides warmth while also dissipating heat during periods of high output. And finally, the third layer, the shell, which is the most weather-protective layer, worn on the outside of all other layers.