Lightweight insulation and comfortably soft fleece lining combine to make the north face inlux jacket one of the most popular insulated layers in this category the heatseeker synthetic insulation is famous for its warmth durability and weight making it ideal for coldweather activites whilst the hyvent 2 layer construction prevents overheating by wicking sweat before it has time to cool fully integrated into a technically high performance shell under arm vents comfort cuffs storm fla