Spark Women's dunsovepose

The second highest-lofting down used in any of Sea to Summit’s sleeping bags or quilts. 850+ Fill Power indicates that one ounce (30g) 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 our non-PFC Ultra-Dry Down™ treatment.

The QuiltLock system 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 quilt now works for ultralight summer adventures and turns your three-season bag into a four-season sleep system.

100% of the down used in our 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. To learn more about RDS visit textileexchange.org/responsible-down-standard/

Our Free Flow triple-zip design ensures your sleeping bag retains maximum warmth and efficiency when needed and multiple ventilation options when it's not.

The (half-) zip on the right side of the bag (left side on women's bags) provides freedom of movement for both arms, additional ventilation and allows (the top third of) the bag to be folded down as a (mini) quilt when the mercury climbs higher than expected.