Big Agnes Elk Park -20 (Thermolite Extra) Sleeping Bag Big Agnes removed the insulation from the bottom of the bag and designed it to be used with a corresponding sleeping pad, thus providing an integrated sleep system with everything you need and nothing you don't New design improves connection between pad sleeve and bag providing a roomier sleeping space without adding bulk New contour allows the bag to drape around you, increasing insulation performance Stretch fabric panels on the side of the pad sleeve accommodate different pad thicknesses Corner hand pockets allow top of bag to be wrapped around shoulders much like you might with a comforter in a bed