Mountain Hardwear Lamina™ -20F/-29C

The Mountain Hardwear Lamina -20F/-29C sits at the extreme-cold end of the Lamina lineup, rated by the manufacturer to a -29°C lower limit and classified as a 5-season expedition bag. Warmth comes from a generous 1895 g of TemperLite synthetic fill, welded into the seam-free Lamina baffle system that avoids the cold spots typical of sewn-through construction, with a shaped draft collar and full-length two-way zipper sealing in heat around the neck and seam. At 2300 g total weight and 16.2 L packed volume, this is a bulky, heavy bag by any measure – expected for synthetic insulation built for sub -20°C temperatures, since synthetic fill needs roughly twice the mass of down for equivalent ratings. The payoff is reliability in wet winter conditions where down loses loft, plus a coupleable zipper that lets two compatible bags be joined for shared-body-heat use. The 20D polyester ripstop shell and nylon liner carry a DWR finish; regular sizing suits users up to 183 cm. This is a winter-expedition tool, not a three-season or ultralight backpacking bag.