Sea to Summit's Spark Ultralight Sleeping Bagis engineered to keep you warm at the lightest weight and smallest compressed size._Ultralight doesn't mean cramped; the Spark's snug mummy shape is designed to keep the heat in, but still gives you enough room to move comfortably after a long day on the trail. Ideal for fast-moving, backcountry explorers who don't want to carry a gram more than they need._Suitable for lightweight liners and summer getaways as well as warm, packable bags that'll see you through chilly winter nights. Designed with premium materials and a fuss-free focus on performance, these bags keep things simple without skimping on quality._850+ FILL Power, RDS-certifiedGoose Down with Ultra Dry Down treatment for improved water resistance in damp conditions10-Denier Nylon shell and lining10-Denier Nylon waterproof-breathable hood and footboxMummy Fit: Fitted cut with generous footbox and technical hood, to maximise thermal efficiency and minimise bulk and weightSpark 7C/45F & 1C/30F Primary zip - 1/2 length #5 with zip-plow and two slidersSpark -9C/15F & -18C/0F Primary zip - 3/4 length #5 with zip-plow and two slidersVertical chest baffles, horizontal baffles lower half and baseSPARK 7C sewn through quilted construction throughoutSPARK -1C/30Fbox wall baffles top half of bag and sewn through quilted construction lower half. SPARK -9C & -18C box wall baffle construction throughoutSpark 7C, -1C & -9C Standard front draft collarSPARK -18C Double draft collarsSpark 7 & -1 can't be pairedSpark -9 & -18: Pairs with Women's Sea to Summit bagsQuiltLock System integrates with StS quiltsBest Use: Ultralight BackpackingComes With: Ultra-Sil compression bag and storage cellInsulation: Ultra-Dry Goose Down 850+ LoftMaterial(s):10-Denier Nylon shell and lining10-Denier Nylon waterproof-breathable hood and footboxShape: Mummy Fit: Fitted cut with generous footbox and technical hoodBEST USE: Ultralight adventuresPERFORMANCE: Small pack sizeWEIGHT: 1113g