Air-bag packs, which inflate instantly to keep wearers afloat in an avalanche, successfully saved 13 skier and snowboarder lives in the past two years. If you're in the deep backcountry, you need one. Our choice? The four-pocket Mammut Ride R.A.S. Avalanche Pack. It's roomy, comfortable, and, when emptied, can legally be taken aboard planes. [starts at $700; mammut.com]