Here's a little video from the Therm-a-rest folks that talks about what the Oberon can do for you. And how it does it.

The hood is incredibly warm and closes with a simple zipper-guard snap. Yes, you got that right...good to 0°F or -18°C (more on that later). On your right, note the zippered closure (for a mobile phone or what-have-you). The fill is treated with Nikwax hydrophobic. Check out the silvery colour inside the zippered opening. It's the thermocapture liner that radiates heat back into the bag's inside.

Like most all sleeping bags from Therm-a-rest, the Oberon features these SynergyLink connectors—see the tie-in loops at left and the "strapping" at right. With this system, the bag stays put on the mattress. It seems like a really good and simple idea, and it is.

Here's a view of the SynergyLink system in action. Note that the bag has less down on the bottom because the insulative properties of a good mattress—like the Therm-a-rest Neo Air— make much of underside insulation unnecessary. 

Here's the nitty gritty in terms of how warm it'll keep you. All the good bags these days seem to have this rating system. In essence, it admits that the "comfort range" of the Oberon is 14°F or -10°C. If the mercury drops to -40°C/F, you're going to be in trouble. 

The toe-box is ginormous and features something called the Toe-asis. Essentially a bonus little down "cubby" in which to tuck your tootsies for added warmth. 

Beware the Oberon pupa. Ensconced in 800-fill down (and likely sampling the Toe-asis). 

Here's one spot (above and below) in the Kootenays were the Oberon came in handy. The flue on the wood stove was malfunctioning so it got really cold in the middle of the night. No problem with El Oberon.

• 800-fill Nikwax Hydrophobic Down
• SynergyLink Connectors
• Thermacapture Lining
• Zoned Insulation
• Toe-asis Foot Warmer Pocket
• Quilt and Blanket Loops
• Responsible Down Standard Certified
• Compression and home stuff sack

We've tested the Oberon on cold, shoulder-season paddling adventures, hut- and tent-based ski touring adventures, and sleep-in-the-garage-in-the-middle-of-winter adventures (don't ask). The Oberon has delivered comfort and joy in all situations.

I find that I get really twisted up in many sleeping bags. I'm not an overly active sleeper but I find that many mummies have me in knots by 4 a.m. The Oberon has been designed as a comfy mummy. Hip and shoulder girth (at 58 and 165cms, respectively) give you room to move. The Synergylink program adds to your comfort. SynergyLink's key benefit is that, by attaching the bag and the mattress, you can move independently—thereby avoiding the 4 a.m. pretzel phenomena. This is particularly appreciated in a smaller context, like a two-person tent.

Being just slightly over a kilo for a winter bag can make a big difference on the uptrack. You can't tear a heavy bag in half and share the weight with your trip partner—what you have is what you carry. The light weight is part of the "zoned insulation" approach. Why have insulation where you don't need it? Smart.

I also really appreciate the little features like the heat-trapping draft collars, the cinchable hood, and the outside zip pocket. It's like the Therm-a-rest designers have created a bag with many creature comforts, while not sacrificing on the performance. Double double.

Only downside... and I am a little ambivalent on this: the colour might bring on an acid flashback in some people. I like it (in the same way I do shag carpet).