Updated for 2019, the Spark SPI 5C Sleeping Bag from Sea To Summit combines a superlight but high-loft sustainably sourced down insulation with minimalist fabric construction. This season sees a few key updates to the spark series, including vertical chest baffles that stop down shifting laterally and increase warmth during the night. The RDS 850+ Loft premium goose down, light-gauge #3 YKK zip and high performance 10D Nylon shell and 7D lining fabrics, set the stage for superior performance. A squarer footbox is designed to keep your toes cosy on colder evenings.
The Spark is an impressive hard-alpine or adventure racing bag, where every gram is counted and down has never been a viable option.