Always a favorite of the ultralight elite, the Z Lite SOL expands upon the utralight performance of the Original Z Lite by adding our reflective 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 pad 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 idealclosed-cell foam pad for those in need of an ultralight, highly compact and super-reliable sleep system.