We take shelter at base camp in the -20 Degree Down Marmot Col Sleeping Bag when the low pressure freezes our summit plans. As the roaring whistle of the wind bangs against the tent all night, all we feel is the unmatched warmth of 800-fill goose down inside the Col MemBrain's waterproof, breathable Pertex Shield shell. A down-filled draft tube makes sure that our head doesn't get too cold, and a hidden pocket lets us keep a few items close at hand and out of the cold.