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-PFC 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-PFC 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. Details & Design: RDS-certified, 850+ fillpower goose down with a non-PFC Ultra-Dry down treatment for maximum thermal performance Ultralight, breathable 10D nylon liner and a 10D shell with PFC-free DWR keeps the hood and footbox highly water resistant YKK #5 zippers with zipper plow provide reliable, snag-free operation Technical hood and anatomically-shaped footbox provide excellent warmth retention without the claustrophobic feel of some ultralight bags Women's specific fit means more narrow at the shoulders (for reduced weight) and wider between the hips and knees to allow for a natural, side-sleeping position Sewn through for lighter weight (7degC|45degF), hybrid box baffles in torso/sewn through in leg area (-1degC | 30degF) or full box baffles for maximum warmth (-9degC | 15degF) Technology: Ultra-Dry Down(TM) uses a non-PFC hydrophobic treatment to ensure it absorbs less moisture and dries more quickly QuiltLock(TM) system uses the snap locks located at the shoulder and foot plus the quilt footbox / quilt straps to secure a quilt to the sleeping bag