Valandré Thor Neo and Odin Neo

One of the many cruxes, literally, of winter mountaineering is getting a good night’s sleep. Over the past December and January, I tested two sleeping bags—the Odin Neo (for use down to -22 degrees) and the Thor Neo (-40)—from the French company Valandré, which specializes in down garments and bags.

As a guide in the White Mountains of New Hampshire, and as a long-suffering Alaskan climber, I’ve spent innumerable nights out in miserably cold conditions. At 6 foot 1 inch and 165 pounds sopping wet, I invariably crawl into my bag, get two hours sleep, wake up freezing again, add a layer, pee and lapse back into that brand of tepid shut-eye forever associated with things like airplane flights and alpine starts.

The Valandré bags, though, offer plenty of room and are warm and intelligently built—you can actually get good sleep in them. Why? Instead of mimicking other cold-weather bags and their small foot areas, the Odin and Thor have roomy foot boxes with ample space for hot-water bottles, inner boots, drying gloves, satellite phones, etc., without compressing the down and freezing your feet. This cargo room is an absolute must for sub-0 bags, and the space difference is as noticeable as the legroom between first class and coach.

Fast-and-lighters might decry that roominess, but it doesn’t add significant weight compared to other models with the same temperature ratings: the Thor comes in at 4 pounds 1 ounce; the Odin is 3 pounds 9 ounces.

The most striking features of both bags are their 32 smallish individual down compartments. Most bags “lose” down in certain areas when it migrates across the baffles. With these compartments, smaller and more numerous than in most other bags, Valandré has solved this problem. Down stays put, you stay warm. The down itself is 850-fill, 95 percent big clusters and 5 percent filaments and microfeathers of “fatty” gray geese from Southern France. “Fatty” refers to the strong, fresh and clean down produced by a fully mature bird during its fourth and final molting cycle. This mature down has a higher insulating capacity than down produced during previous molting cycles. As a result, the Odin and Thor do surprisingly well in wet, wintry weather, and the breathable fabric disperses moisture from the bag over the course of a night.

My one complaint about both bags (which differ only in the amount of down they possess) is that the draft collar is complicated with two Velcro closures and drawstrings. I tested the Odin during two separate mountaineering courses, both in subzero temperatures. I was able to sleep comfortably, making adjustments quickly and without rolling and fumbling around too much: The zipper works well and rarely gets stuck in the baffles of the bag.

The Thor is the Arctic explorer’s or Denali suitor’s dream: a -40 bag for long stays in frigid environments. I tested it during a Presidential Range Traverse this past winter, with temperatures well into the negatives and comparable to the lows I’d experienced in the Alaska Range. It was great to strip down to my long underwear, toss everything inside the bag, and still feel like I had plenty of room to move around.

This article originally appeared in Rock and Ice issue 241 (April 2017).