The Big Agnes Lost Ranger 3N1 15° is the lighter, three-season member of the modular 3N1 line — unlike the winter-rated 0° version it is tested to EN ISO 23537 (comfort -3 °C, limit -9 °C) and has a semi-rectangular rather than pure mummy shape. The fill is 650-fill hydrophobic down weighing 532 g, and a total weight of 1272 g works out to 141.3 g per degree.
Sewn-through construction, without baffle chambers, is lighter but less thermally efficient than baffled insulation — a logical trade-off for a temperature class where extreme cold is not expected. A zipper on both sides carries over, along with a recycled 20D polyester shell with DWR treatment, RDS-certified down, and bluesign and PFC-free status.
An insulated collar and draft tube along the zipper, pad loops for anchoring to a sleeping pad, and an included stuff sack and storage sack round out the kit. The cut is men's, up to 182 cm. As a standalone piece of the modular system it suits spring and autumn trips; combined with the matching outer shell it covers colder nights too.