Synthetics are ineffective below -17c.
Really? I'm glad no one has told my synthetic shelled, synthetic filled sleeping bags this- I've used them nested down to about -30F (about -35C) and been very comfortable while wearing a pair of synthetic long johns. Although my watch cap and socks were wool- maybe they alone kept me warm.
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-IronRaven
When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.