The Superior Cocoon is a revolutionary new type of top layer insulation. The Cocoons zips right onto the Superior or StarLite Hammock to create a warm draft-free seal. The bottom half zips in all the way to zipper at the end of the hammock. And the top part extends to full body length up the the shoulders. And because it only uses half of the zipper on the hammock, the other zipper half can still be used with our Half BugNet. The dimensions of the Cocoon do not in any way restrict a great diagonal lay. This design requires less overall down to achieve the same warmth because there isn't any down wasted along the side of the legs. \n \nThe Superior Cocoon is perfect for mild weather, ultra-lighters trying to shed a few ounces, or for winter camping when paired with another Comforter or Top Quilt underneath.