Synthetic bags are great for wet-weather camping, but the tradeoff is usually extra bulk. Not here. The Boreal stuffs smaller than a Nerf, thanks to PrimaLoft Infinity, a new continuous filament insulation that compresses extremely well for a synthetic, plus low-bulk ripstop nylon shell fabric. It's also cut on the trim side, which saves weight and material, but you better check fit and roll-around comfort before buying.
The bag kept one of our cold-sleeping testers warm on freezing December nights in southern Utah, but he and others peg the 20°F temperature rating as a few degrees optimistic. Bonus: A small interior stash pocket is placed at an unusual–and handy–location, right at your chin. And while the fleece-lined stuff sack is a little heavy (3.3 ounces), it turns inside out to make a plush, nonslip pillow. $139; 2 lbs. 13 oz.; 20°F