When both warmth and low weight are crucial, the Ultrasphere 5 is the ultimate packable, featherlight air mat, honed for fast-paced exploring in demanding mountain conditions. Its groundbreaking design includes two layers of TILT, which boosts the mat’s warmth-to-weight ratio by reflecting heat back towards your body, all for a fraction of a gram. It also features new offset air chambers that trap heat within the construction, allowing you to recharge comfortably without the need for high-volume insulation. Highly comfortable and supportive, the Ultrasphere 5 is the ideal foundation for thru-hiking, bikepacking, and multi-day mountain runs.