Cumulus Aerial 250

The Cumulus Aerial 250 is a minimalist down sleeping bag built around a zipperless, false-bottom design — instead of a conventional side zip, the bag closes with a construction that eliminates the weight and potential cold spots of zipper hardware entirely. Filled with 250 g of 900 fill power goose down arranged in H-shaped baffles, it delivers a manufacturer-rated comfort temperature of 2 °C at a total weight of just 385 g, putting its warmth-to-weight ratio well ahead of bags with conventional zip closures. The shell is Toray Airtastic at 19 g/m², an extremely light fabric that keeps total weight down but demands careful handling to avoid snags. A 3D anatomical hood, trapezoidal foot box, and differential cut point to a mummy shape tuned for sleeping-bag-only use rather than versatility as a blanket. Rated 3-season and sized for users up to 185 cm, it suits ultralight thru-hikers optimizing for milder shoulder-season nights where every gram in the sleep system matters.