I’ve been a big fan of this British company’s garments for several years; they are a perfect fit for all things Wasatch winter- and beyond. I’d never been familiar with their bags however, and they are indeed on par with the garments. The best thing is the 800 fill power fluffed inside a lightweight Pertex shell, which is- I’ve found- the perfect combination of insulation and shell fabric for the person looking to go light- think mountaineering, overnight ski tours, etc. The Neutrino 400 checks in at ridiculous 28 ounces, and is comfortable at 2 degrees, although the company maintains that in extreme conditions it would be usable to -20. The mummy taper design is built to maintain heat close to the body. Even the stuff sack is technical- a dry bag, with sealed seams, with a roll top and buckle closure. No more plastic bags needed to keep your bag dry- brilliant! $379 www.rab.uk.com