Built for women who want minimal weight but maximum comfort in their adventures, the Women's Spark lineup demonstrates Sea to Summit's 100% commitment to building a sleeping bag that's made perfect for you. Women's specific shape and body mapping result in warmth and comfort without the weight. RDS-certified 850+ fillpower goose down treated with a non-PFAS Ultra-Dry Down treatment provides superior insulation, while a technical hood and zipper draft tube prevent precious warmth from escaping. A super-breathable 10D liner fabric rounds off the comfort profile, and a 10D shell with a non-PFAS DWR combined with a highly water repellent hood and footbox fabric keep moisture out Couples can zip the full-length zipper Women's Spark to an equivalent Unisex Spark for extra comfort and thermal efficiency. Features RDS-certified, 850+ fillpower goose down with a non-PFAS Ultra-Dry Down treatment for maximum thermal performance Ultralight, breathable 10D nylon liner and a 10D shell with non-PFAS DWR keeps the hood and footbox highly water resistant YKK #5 zippers with zipper plough provide reliable, snag-free operation Women's specific fit: narrower at the shoulders (for reduced weight) and wider between the hips and knees to allow for a natural, side-sleeping position Technical hood and anatomically-shaped footbox provide excellent warmth retention without the claustrophobic feel of some ultralight bags Baffle construction specific for each use: Sewn through for lighter weight (7°C|45°F), Hybrid box baffles in torso/sewn through in leg area (-1°C | 30°F) or full box baffles for maximum warmth (-9°C | 15°F) Sea to Summit Guarantee is offered for the Lifetime of this product