The Spark Pro has been optimized for comfort, versatility and light weight. Our highest-lofting down - 950+ fillpower RDS-certified goose down with a non-PFC Ultra-Dry Down treatment - is wrapped in extremely breathable 10D fabrics. The Free-Flow Zip system ensures maximum ventilation and the flexibility to open the bag flat as a quilt. Zip a Spark Pro to a Women's Spark and share the comfort with your companion. Features RDS-certified, 950+ fillpower goose down with a non-PFC Ultra-Dry Down treatment for maximum thermal performance Featherweight 10D nylon shell with non-PFC DWR, and a highly breathable 10D nylon liner for enhanced comfort Technical hood, anatomical footbox and an ergonomic mummy shape - ultralight doesn't have to mean ultratight Free-Flow Zip System: YKK #5 side zipper with zipper plow for reliable, snag-free operation. YKK #3 footbox and shoulder zipper for minimal additional weight Baffle construction specific for each use: Hybrid box baffles in torso/sewn through in leg area (-1°C|30°F) or full box baffles for maximum warmth (-9°C|15°F) Front draft collar is fitted around the neck and oversized at the shoulders to retain warmth Sea to Summit Guarantee is offered for the Lifetime of this product Features: - RDS-certified, 900+ fillpower goose down with a non-PFAS Ultra-Dry Down treatment for maximum thermal performance - Free-Flow Zip System: YKK #5 side zipper with zipper plough for reliable, snag-free operation. YKK #3 footbox and shoulder zipper for minimal additional weight - Vertical chest baffles, horizontal baffles lower half and base, box wall baffle construction throughout