Cold weather camping has a unique set of challenges, including melting snow and condensation inside your tent. Designed to outperform standard down bags, the award-winning Sierra Design Zissou 0 Sleeping Bag features 33-ounces of 600-fill DriDown insulation to keep your bag insulating better, lofting higher, and drying faster in any winter environment. Simply put, DriDown represents the evolution of down insulation. Regular down is treated with a molecular level polymer to create a hydrophobic finish on each individual down plume. This finish allows DriDown to stay dry longer, loft better, and dry faster than regular down, keeping you warmer in any environment.