I've always preferred closed-cell pads to inflating models as outdoors I've always been afraid of inflatables springing an irreprable leak, making them useless as it's the layer of air in an inflatable that insulates you from the ground. Otherwise, it's jsut a plastic two-ply seet, and you've got nothing between you and the heat-sucking cold of frozen tundra or an ice cave floor, and that's just miserable...if not life-threatening.

Now, the Hyper-Mountain sleeping mat is a hybrid: it has both an inflatable section for the upper torso, and a non-inflating lower section made of EVA foam; the inflatable chest and lower-torso sections (seen in the phot0) are also insulated with Aspen Aerogel's revolutionary aerogel, the 'frozen smoke' designed to insulate space suits; it's the same incredible material used in the ToastyFeet insulting footpads I've also reviewed here, and it works just as well (more on this below.) The whole mat is mummuy-shaped in plan view so as to cut down weight, a good idea (I don't roll around much outdoors, so the "missing" segments that would normally be out the sides of the lower legs was not missed).

Rolled up for transport, the pad was 20 incehs long by 8 inches diameter. That's a little thick (in diameter) compared to many pads, such as the Thermarest. Stowed on the back of an alpine pack it might be a bit bulky, especially if you're headed into fiddly chimney-type terrain--though I haven't used it for climbing. For trekking (or, in my case, dragging on a sled), this should be no issue.

In use the pad worked well, despite somehow being punctured. I haven't found the leak, but I had a puncture which prevented full inflation of the inflatable chambers. Nevertheless, the aerogel seemed to work; I was in -30F to -40F conditions, using the mat on sea ice or tundra. Sometimes I had a thick EVA foam mat under the Hyper-Mountain (as you see in the photo, behiond the gray-and-orange mat reviewed here) but other times I just used the Hyper-Mountain, and was still fine. I can only imagine the aerogel was doing its job. The gel, a white powder, is now leaking out of one puncture in the area below the inflatable sections, and it's a very fine white powder that feels very dry to the hands and I have an intuitive feeling that inhaling this stuff would be really bad; a patch job is needed. The pad comes with a patching kit, but that's for the inflation chambers. I was jsut too busy and too cold to mess around with that patching work, and didn't need it anyway.

I give the pad thumbs up for the mummy shape and use of aerogel, both of which are great -- but a slight thumb-down for duability. I'm careful with my gear, but just can't tell how I punctured it. I'm sure it wasn't crampons or ice screws, as I keep these well away from my soft goods. I don't know if the 28 days at -30F to -40F is esponsible, but it may be. I've found that around -35F things start to go wierd...everything seems to fall apart.

Personally, if I were Pacific Outdoor I'd see if it's possible to just ditch the inflatable sections and stick with an all-aerogel mat. If the durability problem can be addressed, a mummy-shaped, all-aerogel mat would be tremendous. As the price of aerogel comes down, I imagine this will be the ultimate solution.

The standard model is 72 inches long: it also comes in a 2/3 length version ostensibly for mountaineering, however because of the possibility of puncture, I won't ever use an inflaable for mountaineering.

I will, though, continue to use this mat, and I give it a full thumbs-up overall, especially for 99% of uses, in which you can make a repair, and are working in a normal backpacking temperature range, e.g. a little below freezing at worst. For these conditions, I think it's a great choice, and though a little pricey, it's very comfortable...and a good night's sleep...well, that's worth plenty.

Item link here.