Review: Buying Right

From here to eternity ... or at least October
By Kent Black

We consider three-season bags those advertised to keep you warm around 10 or 20 degrees, and which should keep you warm at zero if you pull on fleece tights and a sweater. In short, one bag that'll handle most non-life-threatening weather conditions. Herewith, six of the best.

1. In the Wizard, Marmot makes great use of Polarguard 3D, a polyester that doesn't separate or bunch up and that's lighter and more compact than other synthetics. The Wizard ($169; 707-544-4590) is rated to 15 to 25 degrees, yet it sleeps much warmer, perhaps because of the flannel-like DriClime lining, a brushed polyester that wicks away sweat. Outside, the nylon shell has a durable water-repellent coating that repels morning dew. The narrow mummy shape and trapezoidal footbox are fine for people who sleep on their backs but constrictive for tossers-and-turners.

2. Mountain Hardwear's Polarguard 3D 1st Dimension ($185; 510-559-6700) is an excellent 30-degree bag that weighs less than 2.5 pounds. It's a little short on room but long on features: The foot and shoulder areas are a bit cramped, but you get a handy mosquito net tucked into a pocket on the front of the bag. That's three seasons. If you want to stretch those limits, zip in Mountain Hardwear's 575-fill down liner ($160), which boosts the temperature rating to 5 degrees and the weight to 4 pounds, 14 ounces. Shoving this highland hide-a-bed in your pack is another matter:Bundled separately you have one 7.5-by-16-inch sack and another that measures 6.5 by 12 inches. Zipped together, they cram into one 8-by-22 inch parcel — with the coaxing of a few colorful exclamations.

3. EMS's roomy, semirectangular PLL 20 ($180; 888-463-6367) uses a descendent of Primaloft, a great but bulky insulator. This bag avoids becoming a hay bale when rolled up thanks to Primaloft Lite, which is 20 percent lighter than its forebear, but just as warm. (It measures 8 by 16 inches when stuffed.) The 20-degree bag's ripstop nylon shell turns away summer drizzles with its water- and wind-resistant Pertex coating, but it has no hood. And although the stuffsack won't warm your head, it's lined with fleece, so with the addition of a couple of T-shirts it becomes a homey pillow.

4. The Sierra Designs Convertible ($200; 800-635-0461) has an extra layer of Polarguard 3D on one side — put the thick side on top when it's cold, flop it when it's warm. The bag is rated to 15 to 30 degrees, but like a ragtop Mustang it's best suited to fair-weather excursions. Of course, the design means the bag can't have a hood, so bring your balaclava. It's not especially wide across the chest, but the boxy shape still allows for squirming. The full cut makes it bulky — it compacts to 10 by 20 inches — but the bag excels in the comfort zone.

5. It may seem odd that Moonstone named its 800-fill down bag after the notoriously damp Pacific Coast Trail, the last place you'd want to be stuck with soggy down. However, W. L. Gore's Dryloft, which is laminated to the shell to keep insulation dry, is a down bag's best friend. The PCT ($390; 800-390-3312) has a wide temperature rating — 10 to 25 degrees — and inside it on a 9-degree night I was comfortable in tights, socks, and a Polartec T-shirt. Conversely, it'd be too toasty for midsummer lowlands.

6. Check out the stats of the Feathered Friends Swift ($393; 206-328-0887): a 20-degree bag that weighs 2 pounds, 4 ounces, and stuffs to the size of a regulation football. The secret, naturally, is 750-fill down encased in a Dryloft shell. The mummy shape is generous across the chest and tapers gradually to balance warmth and room to move, and the hood snugs down nicely, though it fits like a skullcap. For the shell, Feathered Friends chose an uncommonly light 1.1-ounce nylon, which doesn't crinkle quite as loudly as the ususal stuff, so your tentmates won't be botherd by your restless dreams.