The Spark Ultralight Mummy Sleeping Bag Series spans everything from an ultralight down-filled liner, to a mid-winter fast-and-light sleeping bag. Each model uses premium materials and no-frills design to provide cutting-edge performance.

Ultralight does not mean ultra-tight: The Spark mummy sleeping bags are snug but still have adequate wiggle room for the performance-oriented, backcountry user.

Technical features

Features

• 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.
• Spark 7C/45F & 1C/30F Primary zip - 1/2 length #5 with zip-plow and two sliders. Spark -9C/15F & -18C/0F Primary zip - 3/4 length #5 with zip-plow and two sliders.
• Vertical chest baffles, horizontal baffles lower half and base. SPARK 7C sewn through quilted construction throughout. SPARK -1C/30Fbox wall baffles top half of bag and sewn through quilted construction lower half. SPARK -9C & -18C box wall baffle construction throughout.
• Spark 7C, -1C & -9C Standard front draft collar. SPARK -18C Double draft collars.
• Spark 7 & -1 can't be paired. Spark -9 & -18: Pairs with Women's Sea to Summit bags.
• QuiltLock: Every Sea to Summit sleeping back features the QuiltLock system that uses the snap locks located at the shoulder and foot end of Sea to Summit sleeping bags plus the quilt footbox / quilt straps to secure a quilt to the sleeping bag. This adds thermal performance and versatility to your sleep system: your integrated Sea to Summit quilt now works for ultralight summer adventures and turns your three-season bag into a four-season sleep system.
• Draft tube