The Chrysalis 20 is a 900-fill down sleeping bag, purpose built for ultralight backpacking. We made every consideration to minimize weight while maintaining comfort, to the point that we removed unnecessary insulation from the back of the bag, where the sleeping pad would typically be. It'll keep you cozy at night but won't weigh you down during the day.900 fill down is extremely compressible and ultra-lightweightMade with lightweight yet durable nylonPanels on back of sleeping bag are built without insulation to save weight without compromising warmthCinchable, insulated, flat hood decreases weight without compromising warmthIn addition to the full-length zipper, there's a short side zipper that you can unzip to extend the temperature versatility of the bag in warmer weatherThe lightweight YKK zipper extends from the top of bag to the waist, which saves weightCompressible nylon stuffsack is made with durable Cordura ripstop to help protect the bag from abrasions while it's inside your backpack