Always a favourite of the ultralight elite trekkers, the Z Lite SOL from Therm-a-rest expands upon the utralight performance of the Original Z Lite by adding a reflective ThermaCapture coating to capture radiant heat and increase overall warmth by nearly 15%. Factoring in the system of heat trapping dimples, the Z Lite SOL has an R-Value of 2.0, making it perfect for use on its own in warmer weather or layering under another mat for extra warmth in the cold. The proprietary foams are softer on top for extra comfort and denser on the bottom for extra durability, making the Z Lite SOL an ideal closed-cell foam mat for those in need of an ultralight, highly compact and super-reliable sleep system. Z Lite SOL Sleeping Mat