Marmot Electrum 30

Best For:
 Efficient warmth.
The Test:
 The human body doesn’t lose heat evenly, so Marmot’s designers decided that uniformly insulating a sleeping bag only adds cost and weight. Instead, they used heat-mapping technology to determine where to add insulation (torso and feet). And then, because synthetic fill provides more thermal efficiency than down when compressed, they decided to stuff the Electrum ($159) with synthetic on the back and 650-fill down on the front. Result: the Electrum is toasty and fairly compact, squishing to the size of a cantaloupe.
The Verdict:
 A brilliant bag from top to bottom. 30°; 2.5 lbs; marmot.com
Sleep Comfort 
4
Warmth to Weight
 3.5