Western Mountaineering Sleeping Bag Features

Shapes and Names

Four main styles constitute the Western Mountaineering sleeping bag lineup.


Semi-Rectangular bags are wide at the head and foot for bigger folks or for roomy comfort, and they're named for trees of the North American Forests: Tamarack, Sycamore, Alder, Ponderosa, Sequoia, and Bristlecone.

Wide-Cut Mummy bags have wide shoulders (62"-66") tapering to a narrower footbox. These bags are ideally shaped for lightweight mountaineering and named for North American Mammals: Caribou, Badger, Antelope, Kodiak, Lynx, Puma, Bison.

Mummy bags feature a narrow and weight saving cut that is more temperature efficient than the wider bags. Named for the Native American Tribe, the "Apache" is arguably the most versatile bag in their lineup, and the only narrow bag offered in MicroFiber and GWS shell fabrics.

ExtremeLite bags offer a mix of all three shapes (Semi-Rec, Wide-Cut Mummy, and Mummy). They are the lightest weight bags available, specifically built for extreme compressibility with weight as the primary consideration. They are easily identified by the suffix, "Lite".

Differential Cut

The hood on your sleeping bag isn't quite like the hood on your jacket. Western Mountaineering uses a "reverse-differential cut" in the hood that actually uses a larger piece of material on the inside. This creates a loose pocket of down that settles comfortably around your head and eliminates the need to cinch the hood tight. The result is dreamy.

A regular "differential cut" is used for the sleeping bag body on mummy bags. The inner shell fabric of the bag is cut to a smaller cicumference than the outer shell, eliminating excess fabric and reducing cold spots. This design also helps the bag to loft up more quickly, and more efficiently distributes the down inside the bag. Semi-rectangular bags don't use this technique. They're designed to lay flat like a comforter.

Continuous Baffles

Western is able to make their three season bags more versatile with the use of "Continuous Baffle" construction. Running across the bag (from zipper to zipper), the baffles hold the down in place and keep it from shifting top to bottom. "Continuous Baffles" purposely allow the down to travel from side to side which allows you to ajust the insulation for the conditions. If it's a 50F night and you're in a 20F bag, you can completely unzip the bag, and use your hands to push the down from the top side to the bottom side. If the down has migrated to the wrong side after a few trips, a quick shake of the bag an manual adjustment will get things back in order.

Down Collars

A full down collar is used all bags 20F and lower. It is sewn in along two seams to create a truly three dimensional tube of down that seals in heat and reduces the "bellows effect" from moving around in your bag at night. Adjustable elastic on the inside lets you to really cinch it down. The entire collar on GWS bags is constructed with Gore Windstopper for extra protection. The Megalite uses a minimalist "passive collar" down tube on the top portion of the bag as a lightweight alternative to the full collar.

Side Block Baffles

Cold weather bags have more down, and keeping that down in place requires the use of mesh "Side Block" baffles. This baffle runs the whole lenth of the bag opposite the zipper and keeps down from migrating top to bottom. For true winter bags Western takes it a step further with "V-Block Side Baffles". These wedge shaped baffles create chambers of down along both sides of the bag, effectively eliminating cold spots.

Stuff and Storage Sacks

Every Western Mountaineering sleeping bag comes with a small stuff sack and large cotton storage sack. The stuff sack is urethane coated for protection from moisture and features a sewn in handle. The stuff sack is sized to fit your new bag, so it is a tight squeeze. Push the sleeping bag all the way to the bottom of the stuff sack and use some elbow grease. It will fit! Gore Windstopper bags are sometimes easier to stuff when turned inside out. It's important to only use your stuff sack for transportation. Leaving the bag compressed can damage the loft of your bag and will jeapordize the longevity of your investment. The provided cotton storage sack allows your sleeping bag to fully loft up and breath while stored.

It's the Little Things

The Western Mountaineeing linup didn't happen overnight. Years of refinement have enabled Western to climb to the top of the heap and created a full spectrum of sleeping bags for every condiditon. It's the sum of the parts that make their bags so great and keeps them in such high demand. Top performance demands top quality. High output requires high efficiency. Making the worlds best bag takes exacting design and a commitment to excellence. Enter Western Mountaineering.