Gear Review: Mammut Ajungilak Alpine Winter Sleeping Bag

A synthetic mummy that's virtually waterproof

This synthetic mummy proves that, at least occasionally, gear performance actually exceeds manufacturers’ claims. Mammut says that the tightly woven prolightTX shell fabric is merely water resistant, but when our AT-hiking tester awoke to find her bag sitting in an inch of standing water, she deemed it pretty darn close to waterproof. “Everything was drenched, including the outside of the bag,” she reports, “but I stayed completely dry inside, and warm down into the high 20s.”

The synthetic insulation (a proprietary fill called MTI 14) is lightweight and compressible—not quite as packable as down, but springy enough to cushion side-sleepers’ hips and resilient enough to maintain its loft through eight straight weeks of use. A three-quarter-length zipper provides venting, and the hood has an integrated pillow sleeve.


3 lbs. 8 oz;

14°F; one size