Remember the trapezoid from 10th-grade geometry? Turns out, this funky ol’ shape is ideal for helping sleeping bag baffles retain heat. The women’s specific Cosmic features trapezoidal baffle construction for increased thermal efficiency—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.