The Therm-a-Rest ProLite Plus Mattress is a self-inflating mattress for sleepy nights on the trail. The Therm-A-Rest Atmos™ Foam is lighter than before, providing four-season warmth with diagonal-cuts in the pad to reduce weight even further. The pad lifts you off of the cold ground and the R-value of 3.4 keeps you warm. Available in three sizes, each has a thickness of 1.5 inches with durable 50D polyester fabric underneath and a softer, yet just as strong 50D mini Hex Rip Polyester fabric on top. Lay out the mat, open the valve, and when you return to your tent for dinner all you need are a few extra breaths of air to adjust for firmness before drifting off to dreamland.