Gear Review: Mammut Eigerjoch/ Biwak Jacket

This coat redefines what warm means.


Unless you’re headed to Everest, this is all the warmth you’ll ever need from a jacket. It’s stuffed to the gills with 800-fill down that stays in place with a double-chamber baffle system that separates the down into triangular chambers with welded (not stitched) seams to prevent cold spots. Puffy swatches of synthetic fill in the back and underarm areas help retain insulating power if those sweat-prone areas get damp. “I wore the Biwak (women’s version) on the summit of New Hampshire’s Mt. Washington on a 0°F February day with wind speeds of 30 mph,” says one tester. “I was immune to the cold.” Long Lycra hand gaiters create an impervious seal beneath gloves and a mini-snow skirt seals the bottom hem from blowing gusts. The brimmed hood fits easily over a helmet, yet the three-point adjustment system and a high chin let you cinch it tight over a beanie to create a goggle-size opening with good peripheral vision. Reality check: It’s overkill for anything but extended deep-winter trips or alpine climbing. $500; 1 lb. 6 oz. (w’s S ); m’s S-XXL, w’s S-XXL;