Bought my Big Agnes Pomer Hoit 0 Degree bag with matching insulated air core sleeping pad. Used the combo for a climb up the remote & seldom climbed north side of Elbrus in Russia end of August, 08. Two wks of use in temperatures to 20 degrees and gale force winds which threatened to rip our tents apart at the foot of the glaciers. The Russian guides were envious while they were cold in their gear and my fellow American climbers were wishing they had the 2 1/2" of comfortable air under their bags. Everyone was surprised by the light weight of the bag/air pad combo. I slept comfortable & warm the entire time. Another plus is having the mattress secure in the bag sleeve so you're not rolling off the mattress.