Big Agnes Lost Ranger UL 3N1 15°

The Lost Ranger UL 3N1 is a modular sleeping bag system from Big Agnes: a mummy-shaped inner bag pairs with a separate outer quilt, and the two can be worn together or apart to give three distinct warmth configurations. Big Agnes rates the setup to 15°F / -9°C at the limit, with a milder comfort point around -2°C, positioning it for cold three-season use rather than true winter. Insulation is 420 g of 850-fill-power down with a DownTek hydrophobic treatment, backed by RDS-certified sourcing and an Ultralight nylon ripstop shell with DWR finish, so damp tent walls or morning condensation are less likely to collapse the loft. A full-length left-side zipper, contoured adjustable hood, internal draft tube, and pad loops for pairing with a sleeping pad round out the build. At 992 g total it's not the lightest three-season bag on the market, but that weight buys real adaptability across a range of temperatures. The cut is men's-specific with a 182 cm max user height, so fit is worth checking before treating it as a do-everything bag.