Big Agnes Bolten SL 20

Few of us slip into our sleeping bags, sleep like rocks, and then emerge, refreshed and ready to carpe that diem. Reality is much less romantic. There’s squirming into the bag, tossing and turning in the night, snapping up into a seated position when a cracked twig evokes the yell, “bear!” from your tent mate. And what about card games, boiling water in the rain, catching a sunrise cliffside while it’s still biting cold?

More and more brands are adding stretch to their sleeping bag designs, hoping to make camping more comfortable and sleeping bags more attuned to the varied needs of a backpacker. Big Agnes’ Bolten 20 does just that: stretchy panels run the sides of the bag, equipped with PrimaLoft Gold Insulation to minimize heat loss and maximize retention (PrimaLoft silver insulates the rest of the bag).

Testers both big and small have pushed the limits of this stretchy bag on backpacking trips and car camping trips in Utah, as well as overnights in Colorado, and we recommend it as an option for folks who love premium synthetic insulation as well as the idea of a stretchy sleeping bag.

Pros:

Testers dug the lightweight feel of the PrimaLoft insulation, as well as the spacious interior and generous cut of the bag. The mummy hood has an adjustable cordlock and holds its shape well, blocking out cold gusts should you choose to sleep out under the stars. If the bag exterior gets wet, the PrimaLoft synthetic insulation retains warmth well, and come morning, you can hang up the Bolten to dry from the exterior loops. The stretchy side panels are definitely the highlight of the bag—they offer some give without reducing the warmth of the bag by offering a bulkier, roomier cut.

Cons:

For the price, the bag is still fairly bulky when stuffed, so it’s not our top choice for backpacking. We’d rather use the cheaper, roomier Big Agnes Sandhoffer or upgrade to either the more compact Marmot Helium or the warmer North Face Inferno. That said, because of the synthetic insulation, this stretchy bag is best-suited for active sleepers who tend to go backpacking and car-camping in wetter, moisture-rich regions like the Pacific Northwest.

Favorite feature: The stretchy side panels, which gives the bag a less claustrophobic or constricting feel.

Tester Comments: “We fell asleep under the stars, and as the temps dropped throughout the night and the wind picked up, the mummy hood held its shape wonderfully and blocked out the cold.”

Bottom Line: A stretchy and innovative option from Big Agnes, the Bolten SL 20 is not your average mummy bag.

Key Attribute: Versatility