Duofold is a name synonymous with base layer protection and they offer several tops and bottoms for different conditions in 3 distinct categories; the Original, Thermal and Varitherm. I will be testing the Varitherm Mid-Weight Brushed Back top and bottom. As can be guessed by the name, the Varitherm line is designed to be useful within a wide range of temperatures. Both utilize the same 100% Polyester material that is said to pull moisture out while locking heat in. It definitely feels softer on the inside. A great feature of the Varitherm line is the flatlock seams. To read the rest of the review please click here.