4Season Explorer Zip XLDescription This 4Season system has advantages when you find yourself in colder weather than expected because it can be adjusted to a wide range of temperature conditions without adding weight or bulk. With just the oversize open cell foam pad, most people are comfortable down to about 40 F 4 C. Adding the space blanket under the pad should take you down to below freezing. The space blanket can be placed above or below the pad depending on the