The Spark Ultralight Mummy Sleeping Bag Series offers a range of options, from a lightweight down-filled liner to a fast-and-light sleeping bag designed for mid-winter use. Each model in the series incorporates high-quality materials and a minimalist design to deliver top-notch performance. Contrary to the misconception that ultralight means ultra-tight, the Spark mummy sleeping bags strike a balance. While they provide a snug fit, there's still sufficient room for those who prioritize performance in the backcountry, ensuring a comfortable experience. 850+ FILL Power, RDS-certified, Goose Down with Ultra Dry Down treatment for improved water resistance in damp conditions. 10-Denier Nylon shell and lining. 10-Denier Nylon waterproof-breathable hood and footbox. Mummy Fit: Fitted cut with generous footbox and technical hood, to maximise thermal efficiency and minimise bulk and weight. Regular: Weight: 363g Fill Weight: 150g Fits: Upto 185cm 1Season. Long: Weight: 387g Fill Weight: 170g Fits: Upto 198cm 1Season.