EMS’s 20-degree Boreal is the first sack to use a new synthetic insulation from PrimaLoft called Infinity, which EMS claims is “18 percent warmer and 25 percent more compressible” than comparable fill. Although it was impossible to test that boast, the Boreal squashes down to the size of a volleyball and easily lived up to its rating: It was plenty warm in just-below-freezing temps on the Oregon coast. The cut is roomy, but the beefy draft tubes and collar trap heat, and the shell’s DWR coating keeps dew and condensation at bay. 20°, 2.7 lbs;