What Our Gearhead(R) Experts Are Saying: "This women's Spark is one of the best warm-climate ultralight bags out there. The fit really matters-it's cozy without dead space that would rob warmth. The 850+ down lofts fast, the hood seals nicely, and it still packs insanely small. Perfect for lightweight summer missions." We grab the Sea to Summit Spark 45F Women's Sleeping Bag when warm-weather adventures demand minimal weight without sacrificing a good night's rest. Women's-specific shaping enhances thermal efficiency by reducing dead air while giving extra room where it's needed for natural, comfortable sleep positions. With lofty 850+ Ultra-Dry Down inside a breathable 10D liner, the Spark maintains a soft, airy feel ideal for summer and shoulder-season objectives. A 10D shell treated with non-PFAS DWR resists condensation and wind, while the highly water-repellent hood and footbox add extra protection in damp alpine environments. The half-length zipper keeps bulk low but still allows for easy venting when nights run warm. Packing down to an impressively small volume, this bag is made for fast, light movement without compromising comfort.