The Helium EQ 15deg Sleeping Bag by Marmot is a 850 down filled bag with an outer shell that is constructed with a MemBrain material that provides your bag with waterproofness, breathability and excellent durability. Insulated with a certified 850 goose down fill with a Nautilus Hood that wraps around your head and reduces heat loss. Stretch Tricot Baffles are integrated into the bag to allow it to be stuffed and unstuffed without tearing the outer material. A trapezoid foot box is designed to be more ergonomic to your actual foot shape making the bottom of the bag wider in the toe area and narrower in the heels. One of the cooler features of this sleeping bag is its zipper guard that keeps the draft tube fabric from getting caught in the zipper and the down fill oversized draft tube that eliminates cold spots.