DESC: The Big Agnes Cross Mountain sleeping bag is incredibly versatile and keeps you warm down to 40F. The Big Agnes Cross Mountain is super lightweight and highly compressible. For 2004, the bags actually test warmer than their temperature ratings, so you'll be able to sleep comfortably down to near freezing. It has a dual-purpose design: Use it as a warm weather summer bag or as an overbag that adds approximately 25 degrees to any traditional 3-season bag for winter camping. Simply insert the 3-season bag inside the Cross Mountain. Its Durable Water Repellent (DWR) outer shell fabric will shed moisture and keep the inside bag dry, ideal for winter conditions. Big Agnes makes sleeping bags without insulation on the bottom of the bag because down and synthetic insulation compressed by your weight loses virtually all of its insulating value. Instead, Big Agnes puts a sleeve in the bag floor into which you slide your sleeping pad, and the top 2/3 of the bag is insulated like a traditional sle