The Helly Hansen Sirdal men's insulated jacket is a comfortable garment featuring a relaxed fit that is perfect for layering. It can also be worn as a stand-alone performance layer in many weather conditions. With its recycled ECOLoft Air SR synthetic down insulation, this mid layer has high-performance warmth-to-weight ratio. This jacket can be worn as a mid layer in a layering system providing comfort and warmth enabling you to regulate your body temperature by wicking moisture away during your outdoor activities. This onion layering system is made of three types of clothing. 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 or 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.