This is it folks! Heaps of advancements in fabric, insulation, and design add up to the most evolved sleeping system on Earth. Incredibly lightweight Pertex fabric forms a water-resistant, breathable barrier against the elements. 875+ fill-power goose down has been updated with our Down Defender treatment offering an extra level of moisture protection for sleeping bags exposed to wet environments. Flow Gate Construction allows warm air to circulate without allowing the down to shift.