The Sea to Summit Ascent down sleeping bag redefines what versatile means in a sleep bag. Complex construction and high-quality down keep you warm when it’s cold outside, while the triple-zipper Free-Flow Zip system ensures you stay cool and ventilated when the weather warms. Insulated with 750+ fill Premium Duck Down that is protected from moisture and condensation with ULTRA-DRY Down treatment. This down is certified in compliance with the Responsible Down Standard (RDS). Lightweight 20D Nylon outer fabric is soft and durable. The complex design of vertical baffles over the chest prevent down shifting as you roll over in your sleep. Horizontal baffles from waist to feet complete the shape. The shaped hood, oversized draft collar, and zipper draft tubes keep the cold out and the warmth in. The unique Free-flow zipper system consists of 3 zippers: full-length YKK #5 main side zip, half-length opposite side zip, and foot zip providing unparalleled ventilation as well as use as a comforter. Plus, Sea to Summits Zipper Coupling allow you to form a snug, double sleeping bag by zipping to any Sea to Summit Womens Altitude, Journey or Venture sleeping bag. Features an internal pocket for phone / headlamp / valuables. Includes lightweight Ultra-Sil compression bag and large storage cell.