The core base layer is a thick, extra warm base for extremely cold conditions. The thermal properties retain the bodies core heat at the highest level in icy conditions and allow sweat to be wicked away quickly from the skin at a rapid rate. The compression weave is designed to cling tight to the body to help with muscle fatigue and rapid wicking. The core should be used in temperatures ranging from -5c to 10c for maximum performance. For warmer conditions the core range is recommended.