Sea to Summit Spark Pro Down Sleeping Bag

The Sea to Summit Spark Pro Down Sleeping Bag is a 3-season mummy bag rated to a 3°C comfort temperature and a -1°C limit temperature, built around 310 g of 900 fill-power RDS-certified goose down (90/10 down/feather ratio) treated with a non-PFAS Ultra-Dry hydrophobic finish. In the 30°F/Regular size it weighs 619 g total and packs to 5.3 L, fitting the Regular size category for users up to 185 cm tall, with 196 cm of internal length and 77.5 cm of shoulder width. The 10D shell denier keeps weight down, and a draft collar seals warmth around the neck and shoulders on colder nights near the limit rating. The Free-Flow zip is the bag's standout feature: it opens flat like a quilt for warm nights or camp lounging, and two bags can be zipped together for couples wanting a shared setup. At 619 g and a 3°C comfort rating, this suits 3-season use rather than winter camping - hikers seeing regular sub-zero nights need a bag with a lower limit temperature, but for spring-to-autumn trips where pack weight matters, the fill power and PFAS-free treatment make it a genuinely lightweight, low-impact choice.