They market it as a "15deg F" bag.

[EN TESTED]26˚F/ -3˚C(Comfort)、15˚F/ -9˚C(Lower Limit)、-19˚F/ -28˚C(Extreme*)

Given that they call it "comfort female / comfort male / extreme female" all in base-layers, on their description page, would you (personally) use it at -11F in the (non-severe alpine) snow? Is it realistic to get another 25deg while sleeping out of more layers or would you opt to go ahead an rent a warmer bag? (I'm guessing the latter, but I am curious how far the general consensus is on pushing a bag's rating. )

And at that point, do you forgo the tent and just use a snow cave to keep the ambient up? :P

Thanks!

-mox

The Bag
Their definitions for the EN ratings

Edited by moxford on 12/26/2012 12:05:54 MST.

add another overbag to get another 15-20F ... then add vbl and clothing

trying to get -11F out of a 15F bag is quite a stretch ... at those temps you have no margin for error

I have always found MB bags optimistic with respect to their warmth rating, despite the restrictions of EN testing. Having said that, Eric is right. Personally, in winter conditions I want a bag that is rated to the expected temps, lest you get into a situation that causes hypothermia or worse. Extreme cold is not an environment to try out some UL tactics that may or may not work for you.

Ure: I have always found MB bags optimistic with respect to their warmth rating, despite the restrictions of EN testing.

"I have always found MB bags optimistic with respect to their warmth rating, despite the restrictions of EN testing."

Also agree. I am a Montbell retailer, (and Valandre) and have tested several of their bags and jackets. While I like their design, I have been disappointed in their warmth ratings as David stated.

I suspect that it could be due to the use of immature down, but that is only a guess.

Valandre', by comparison, uses mature goose down, and I have found their ratings to be spot on.

EN testing is new to the 2012 models and the down fill amount was increased 1-2oz accordingly across the line I assume to meet the spec. The 2011 UL Super Spiral Down Hugger #1 Regular has 567g vs 595g of down in the EN-rated 2012 model.

SS UL #1, I don't know, but I have two MB bags -- UL down #3 and the Thermal Sheet -- and I find them spot on at 30 and 50F respectively. I always sleep wearing long silk base layer plus liner socks -- for comfort and to keep body oil / grime away from the bags.

Edited by ben2world on 12/26/2012 19:23:07 MST.