Mountainsmith Boreas 40
A synthetic-fill bag with ample loft that offers warmth and comfort.
Model: Boreas 40
This synthetic-fill bag is so compact that one of our testers actually thought it was a down bag before she read the tag. The secret sauce is Marmot’s use of two types of short-staple synthetic insulations—a shingled, high-loft fill throughout the bag, augmented by a highly compressible, finer-denier fill in the torso and feet. The short-staple insulations are more compressible than their continuous filament* cousin, and testers were impressed by the ample loft (about six inches). “I was toasty on nights in the upper 20s,” says one 5’8” female tester from Alaska. “Even after the bag got damp from condensation dripping off the tent, I stayed warm through the morning.”
However, a similarly sized male tester deemed the rating about 5 degrees too generous. “On a 20°F night in Alaska’s Chugach Mountains, I resorted to a bag liner and four-season sleeping pad,” he says. The generous cut—60 inches of circumference around the shoulders and 57 at the hips—is best suited to big folks or warm-sleeping skinny ones. “I had plenty of room around my shoulders and hips, which allowed me to sleep in my preferred fetal position,” says one average-size tester.
Props: The Cloudbreak compresses down to the size of a medium watermelon, which is good for this class of synthetic bag. Bummer: The zipper is snaggy. $199; 2 lbs. 14 oz.; 20°F; marmot.com
*CONTINUOUS-FILAMENT insulation consists of hundreds of thousands of parallel, interlocking strands of synthetic fibers that don’t clump or pull apart; it’s bulkier than other synthetics.The Boreas 40° is a hybrid rectangular shaped bag with full length zippers that allows for quilt style use as well. Perfect for summer use and car camping.