Therm-a-Rest Trail Pro (Large) Puncture Resistance: The Toughskin's design sandwiches the mattress's air-holding seal between a top layer of open-cell foam Expandable Foam: Our patented expandable foam helps create a lightweight, compact core without waste. Weight: 910 grams (2lbs) Thickness: 5cm(2 inches) R-Value: 3.9 Stuff Sack A bottom layer of closed-cell foam, then joins them all with our guaranteed foam-to-fabric bond