Actually, many sleeping bags are mateable聴you simply buy one with a left zipper, and the other with a right zipper. But not all bags are mateable, because on some bags the zipper doesn聮t go all the way to the foot of the bag.
Western Mountaineering Antelope MF Sleeping Bag
Antelope MF Sleeping BagOne advantage of zipping bags together is that you actually can get by with a lighter bag due to the gain from mutual body heat. My recommendation is to get a pair of Antelope MF bags. These down-filled bags are conservatively rated to five degrees, are extremely well-made, and weigh two pounds, seven ounces in the regular length. And they聮re mateable. They cost $435 a pop, but they聮ll last pretty much forever.
In a zero-degree bag, 聮s Couloir ($400) also can be purchased with right and left zips and then attached to one another. It聮s a little heavier than the Antelope, at three pounds, three ounces each. But it聮s a high-quality bag, with 800-fill down, a Pertex nylon shell with water-repellent treatment, a snug-fitting hood, and more.
I聮ve recommended down bags because cold-weather down bags typically weigh much less than their synthetic counterparts. But that isn聮t always the case. 聮s Pyxis ($219) is a zero-degree synthetic bag that weighs a very competitive three pounds, one ounce. It might not last as long as the down bags, but it does cost considerably less.
Hope that helps!
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