The Arc'teryx Beta SL women's lightweight hiking jacket is very versatile for mountain environments with its waterproof, breathable and windproof Gore-Tex membrane. Designed with a purposeful simplicity, this non-insulated shell features a trim fit that eliminates bulk, moves with your body and fits comfortably over your insulation and mid layers. Its helmet compatible StormHood gives full coverage without impeding sight. This outer layer is famous for its remarkable performances across a wide range of activities. 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.