An excellent 3-season backpacking sleeping bag that borders on the ability to use in some 4-season applications, the Western Mountaineering UltraLite is best suited for colder sleepers or mid to high elevations during the middle of summer, and is warm enough to take along on late spring or early fall trips in the mountains. The other Western Mountaineering bag we tested in this review, the MegaLite, offers more internal space and being on the warmer side of 30 F bags, is plenty warm enough for almost all 3-season applications. As a result of having less insulation, it is lighter and able to compress to a smaller size.
That's not to say that the UltraLite isn't a fantastic bag, especially for those who want a warmer option than the MegaLite offers. The UltraLite is slightly narrower than the MegaLite; however, even tester Ian Nicholson, a self-admitted broad-shouldered backpacker, didn't mind the slimmer cut of the UltraLite, even while wearing a jacket. If you're a bigger person, and you want a little more space or plan on wearing a down jacket to bed on a regular basis, consider the wider Western Mountaineering AlpinLite.
As with other Western Mountaineering bags, we like that it is made in the U.S.A., uses ethically harvested down and has simple, functional features.