THE SELL: A packable three-season bag with a roomy cut. THE TEST: We were impressed that the Mystic’s semirectangular design didn’t come with a big weight penalty and that such a roomy bag compressed down to the size of a melon. Big Agnes hits the 15-degree rating by overstuffing the bag with high-end 800-fill down and then sealing in that heat with a plump draft tube and unique yoke-shaped draft collar. Like all Big Agnes bags, the Mystic has no insulation on its underside, where it gets compressed. Instead, a sleeve accommodates any 20-inch sleeping pad. THE VERDICT: Rectangular bags aren’t just for slumber parties anymore. 15º; 2.1 lbs; bigagnes.com
Compressibility: 4.5
Warmth-to-weight ratio: 4.5
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