Your sleeping bag can mean the difference between a good nights rest and a miserable sleepless night in the great outdoors. Sleeping bags come in a variety of styles, insulations, and fabrics. Many high end sleeping bags use duck down. Down is one of the warmest sleeping bag insulations available. The bad side of down is that if you get it wet, it clumps together and is basically useless. If you are sure you can keep a down sleeping bag dry, it is the best choice for sleeping bag comfort, warmth, and weight. You'll love the super soft feel of down after a long day on the trail. Down also compresses to about 1/3 of its loft so it doesn't take up much room. There are some great synthetic insulations out there as well. Most of them utilize a polyester fiber making them very versitile. Synthetic insulation doesn't pack as small as down, but it will keep you warm even when it is wet. Synthetic sleeping bag insulation also dries very quickly.