Almost a decade ago, we gave this 0°F bag and others in Marmot’s ultralight series an Editors’ Choice Gold Award for their category-leading performance. In the years since, the Lithium has only gotten better. Its premium 800-fill down is now water-resistant, enhancing loft on extended trips or in wet conditions. Curved baffles limit down shifting and improve warmth. The contoured footbox is larger, and a short, secondary zipper at the shoulder boosts ventilation and makes it easier to get in and out. What hasn’t changed: The shell is still made with light-but-durable Pertex Quantum fabric, a muff around the face seals in heat, and the full-length zipper runs smoothly. Bonus: Compared to a decade ago, the Lithium is the same price (adjusted for inflation) and 2 ounces lighter. And it’s filled and finished at Marmot’s California facility.