The Therm-a-Rest Hyperion 20 Degree sleeping bag’s lightweight insulation and cool-weather features promise a warm sleeping experience for all of your 3-season adventures.The bag is insulated with 900 fill Nikwax Hydrophobic Down. This specially treated down absorbs 90% less water and dries 3 times faster when it does get wet. It’s manufactured without using dangerous PFCs. The bag uses mesh walls to maximize loft and minimize cold spots. A reflective lining traps radiant body heat and retains warmth without adding bulk or weight. Zoned construction saves weight by decreasing fill on the bottom of the bag, where it is compressed by your body and doesn’t provide efficient warmth. Because there is less insulation on the bottom of the bag, you must use a suitable sleeping pad to achieve the state temperature rating. Integrated SynergyLink connectors keep your sleeping pad (sold separately) from moving away during the night. These strips are removable if not needed. A draft collar and zipper draft tube prevent cold air from sneaking inside the bag and the hood can be cinched down to keep your head insulated. Other features include a snag-free zipper, an included compression sack, and a storage sack. The Therm-a-Rest Hyperion 32 Degree sleeping bag comes in different sizes to accommodate different heights. Small fits 5’1” to 5’6”, Medium fits 5’ 7” to 6’, and Large fits 6’ 1’ to 6’ 6”.