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.

Features

• ULTRA-DRY Down 850+ Loft 90 % Down Cluster Premium Goose Down certified
• Responsible Down Standard (RDS)
• 10D shell and 7D liner materials help to achieve the incredible lightweight and compact packed size
• Includes lightweight Ultra-Sil compression bag and storage cell

Zipper-length trimmed for gram-saving performance:

• 50°F, 40°F, and 28°F have 1/3-length zippers
• 18°F and 5°F have full-length side zippers that can be coupled to a Flame sleeping bag with a full-length zipper

Baffle construction:

• 50°F and 40°F have sewn-through construction
• 28°F has baffles in the torso and sewn through in the leg area
• 18°F and 5°F are fully baffled

Shape:

• 50°F , 40°F and 28°F - Contoured mummy
• 18°F and 5°F - Broader mummy

850+ LOFT ULTRA-DRY DOWN

• The second highest-lofting down used in any of Sea to Summit’s sleeping bags or quilts. 850+ Fill Power indicates that one ounce (30 g) of down will re-expand to over 850 cubic inches after compression. Higher loft means that less down can be used to achieve the same temperature rating – important for performance sleeping bags. The loft and down quality / composition are independently tested by the International Down and Feather Laboratory (IDFL) – a copy of the certification is supplied with every Sea to Summit sleeping bag. The down is responsibly sourced and RDS certified and treated with non-PFC Ultra-Dry Down treatment.

RESPONSIBLE DOWN STANDARD (RDS)

• 100 % of the down used in sleeping bags and quilts is independently certified to the Responsible Down Standard (RDS). The RDS certifies down against animal welfare requirements and tracks it from the source to the final product. The purchase of RDS certified products demonstrates demand for better animal welfare practices in the down and feather supply chain. Sea to Summit is certified to the RDS.

UL 10 DENIER NYLON

• Despite being incredibly lightweight, the 10 Denier UL Nylon is down-proof and surprisingly durable. A DWR finish helps to shed external moisture. This fabric is part of the secret to making the Spark and Flame Down Sleeping Bag Series some of the lightest, most packable sleeping bags available today.

NON-PFC

• Sea to Summit sleeping bags do not contain PFCs.
• Ultra-Dry Down uses a non-PFC hydrophobic treatment to ensure it absorbs less moisture and dries more quickly. The treatment does not affect the breathability or the lifespan of the down and lasts through at least 20 washings.
• The down used in sleeping bags is RDS-certified responsibly sourced.
• Down and synthetic-insulated sleeping bags utilize a non-PFC DWR treatment on the shell fabric for external moisture repellency. This helps prevent the insulation from becoming damp if the sleeping bag comes into contact with condensation on a tent wall, for instance.

Tech features

• Best use: Ultralight Backpacking
• Comes with: Ultra-Sil compression bag and storage cell
• Insulation: Ultra-Dry Down 850+ Loft
• Shell fabric: Ultralight 10D Nylon Shell
• Zip options: Spark 0-II: Left-side #3 YKK zipper; Spark III-IV: #5 YKK