The Kelty Cosmic Ultra 0 is the ultimate in a lightweight mummy. We’ve taken our top-selling Cosmic Bag and added an 800 fill DriDown version, with all the perks too. The new trapezoidal baffle construction improves is ideal for retaining heat—and it’s just one of the reasons Cosmic is still our favorite three-season superstar. We also love the natural-fit foot box for happier feet, and a PFC-free water-repellent coating for a healthier environment.