I5 HEADWIND JACKET  A dynamic mid-layer that works hard to keep you comfortable. Using an Intelligent Thermoregulation System the thermal resistance actually changes according to varying weather conditions. The thermal gates within the jacket create a dynamic structure. During colder conditions, these thermal gates are 'closed' and maximum thermal efficiency is achieved. As the temperature becomes warmer, the microspaces start to 'open' and allow excess heat to escape. This ongoing dynamic adjustment helps keep the user in the comfort zone over a wider range of weather conditions when compared to traditional insulation. Wear underneath your waterproof for the ultimate performance layering system regardless of workrate or sailing conditions.