With a traditional mummy shape, and a quilt-style closure, the Sierra Designs Zissou Plus Two-Season Mummy Sleeping Bag is unique, providing more bed-like comfort. It intuitively adapts to varying temperatures, for 2-season use.Traditional mummy shape. Unique integrated quilt: Dual zip and trapezoidal shaped quilt provides bed-like comfort in warm weather. Side wall baffles prevent down migration, keeping you warm. Anti-snag zippers. DriDown 700-fill duck down insulation stays dry 10-times longer than untreated down and dries 30% faster.