Big Agnes sleeping bags are pretty unique. Sure, they're available with down or synthetic insulation, and they are good for sleeping in and all that stuff like that. But here's where they're different: Big Agnes basically integrates the sleeping pad into the sleeping bag. See when you get a Big Agnes sleeping bag and sleeping pad, the sleeping pad slides inside an integrated sleeve in the bag. This does a couple things. First, you don't wiggle off your sleeping pad. Second, it insulates you better. See, when insulation is compressed by your body weight laying on top of it, it loses it's ability to insulate. Big Agnes gets rid of that bottom insulation, and you use the sleeping pad to insulate your back instead. It's really pretty cool.
If you need to shed weight for a backpacking trip, a Big Agnes down sleeping bag is the way to go. Bags range from 600 to 800 down fill power to provide maximum warmth and comfort while keeping weight to a minimum. A down sleeping bag will compress down smaller, too, so it takes up less room in your pack. Big Agnes sleeping bags feature Insotect Flow technology which is an insulation system that redistributes warmth to your extremities. It's really cool.
If weight isn't a huge issue, check out Big Agnes synthetic insulation sleeping bags. Synthetic bags have the benefit of keeping their insulation properties when they're damp and being much quicker drying than down bags. So if your trip is going to be a damp one, check out a Big Agnes sleeping bag with synthetic insulation. Big Agnes uses some sweet technology to ensure a good night's sleep, like A-Flex Construction to increase loft and trap warm air and A-Shingo Construction to create more space where warm air gets trapped.