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.