Western Mountaineering is a California-based company that has been making ultralight down sleeping bags in San Jose for over 35 years. Ask anyone who owns one of these: they are fantastic! But they are expensive, because every model that Western Mountaineering manufactures is insulated with highly compressible 850+ fill goose down. This grade of down provides much better heat retention with less weight than the 550-700 down fill that you’ll find in sleeping bags from other manufacturers. This weight difference is significant in a 20F degree bag like the Western Mountaineering Ultralite 20, but it becomes huge in a -25F degree winter bag like the Western Mountaineering Puma which weighs just 3 lb. 7oz.
In addition to their superior down, Western Mountaineering offers their sleeping bags with three different exterior shell fabrics: ExtremeLite, Microfiber, and Gore Windstopper.
- ExtremeLite shells are made from nylon which is the lightest, most compressible and most breathable shell fabric available. Unfortunately they offer the least protection from outside moisture or tent condensation, so bags with this shell are best used in mild weather conditions and on shorter expeditions.
- Microfiber shells are constructed from tightly woven nylon or polyester with higher thread counts than ExtremeLite. The tight weave of Microfiber is water repellent, more breathable, and lighter weight than that of coated or laminated fabrics such as Goretex. Microfiber shells are a good option if you expect limited contact with water such as tent condensation.
- Gore Windstopper is heavier than microfiber, but it will keep water out of a down bag while allowing vapor to escape, preventing it from reducing the performance of your down bag. This is especially desirable in damp environments such as a snow cave, tent, or bivy sack, in winter conditions.
When buying a Western Mountaineering bag, it’s important that you carefully consider the temperature, weight and cost trade-offs of their different bags and shell materials. I’ve assembled a sortable table below for this purpose. Just click on the model name and you’ll see a popup with the lowest prices available from several different retailers.