Backpacking
Protech Extreme Bag
Ultra-lightweigth waterproof sleeping bag
Check out this bag! The MPI Protech Extreme Bag is really three emergency "space blanket" bags nested inside each other and joined by internal baffles. Since it is reusable, it has promise as a weatherproof replacement for both a sleeping bag and a tent/tarp/bivy. I've been experimenting with this bag on extended canyoning trips where gear is severely abused and repeatedly submerged.�In this situation, a lightweight down bag is perpetually at the mercy of dry bag leaks, and anything else is too heavy and bulky for a small pack. Even though it is presented as an emergency bag, I've used and stowed the Extreme Bag several times with no apparent damage.
Although slightly heavier than a similar-looking Thermo-Lite bag, the Extreme Bag provides significantly more insulation. The Thermo-Lite bag is essentially a reinforced version of the disposable aluminized mylar emergency bivy. It provides a complete wind and vapor block, and some reduction in radiative heat loss, and so as emergency shelter is MUCH better than nothing. However, since it is a single layer and made of somewhat conductive material, it doesn't provide much true insulation. Not really a sleeping bag replacement.
The real insulation in almost any lightweight bag or garment is the air trapped within the down, fiberfill,�etc. The Protech Extreme Bag takes a step in that direction by trapping two layers of air between its innermost and outermost layers. The inner layers are perforated to allow the contained air spaces to inflate easily. The outer layer is NOT perforated and�forms an airtight, waterproof vapor barrier. MPI claims that their Extreme Bag is almost as warm as a typical 3-season sleeping bag. I found it to be comfortable down to 40 F while wearing only light long underwear. A pad is needed underneath to prevent conductive heat loss to the ground.
Two concerns: Perforations in the inner layers allow air to inflate the baffled spaces between layers, but unfortunately, this means that some water vapor finds its way to the outer layer, which is chilled by the environment, and condenses. But the condensation is�not enough to become a concern in the course of a single evening. I think condensation could be largely eliminated by a lightweight vapor barrier worn within the bag. Also, a tan, green, or otherwise neutrally-colored version would be appreciated. The silver version looks like an enormous alien larval pod when occupied...OK for genuine emergencies, but most of the time I'd rather not be so conspicuous. MPI is the same company that pioneered the Space Blanket, which now comes in various colors, so I hope they provide some alternative colors with this bag.
For me, the appeal of this product is a compromise between weight, bulk, warmth, and invulnerability to moisture. It weighs about 12 oz., rolls into a bundle about the size of a very light down bag, is warm enough to be used by itself for cool-weather camping, could be used in the rain without a tent or bivy bag (although a rock ledge, log, or a bit of tarp to stick your head under makes it much more tolerable), and you could literally submerge it for hours without significantly affecting its insulating ability (once squeezed out and inflated).
-- Bruce Weir
Extreme Pro-tech Bag
Available from Northern Mountain Supply
$35
Or from Amazon
Manufactured by MPI Outdoors