Description of Thermarest Regular Prolite 4 Air Matress The lightest, most compact 4-season mattress. Features: Uses: Great for mountaineering, winter camping, backpacking, and multi-day adventures. Ultralight: Innovative new materials reduce weight by 25%. Compact: Tapered ergonomic design rolls up super-small. All-Season: Thick and warm enough for winter camping. Weight: 1lb. 8oz. (680g) Dimensions: 20x72x1.5 in. (51x183x4cm)