Warm and comfortable in the open air The Hyperion sleeping bag from Therm-a-Rest is one of the lightest in its class, while still offering excellent performance in the cold outside air. The sleeping bag uses thermally efficient box-bent construction in key areas to ensure warmth and comfort in an ultra-light package. This bag is suitable for temperatures down to -6 degrees. Designed with high quality materials and the performance features of Therm-a-Rest, the Hyperion keeps your backpack lightweight without sacrificing performance. Storage bag and compression bag included.