Terramar Men's Microthermal Crew ec2 Qwic-Dri Thermoregulation: The ec2 fabric uses electrostatic evaporation instead of standard wicking to release moisture and excessive heat. Standard wicking relies on contact between the skin and the fabric, so the garment needs to be skin tight. The ec2 allows the wearer to have a looser fitting garment for maximum comfort without loosing the ability to thermoregulate. 100% Micro Polyester: Ultra thin fibers of Polyester make up this thermal to give maximum function with minimum weight. Antimicrobial: A treatment to the fabric to prevent things growing where you don't want them to. And in turn, keeps the stink down. Dual layer knit: Two layers of micro yarns to give a soft inner layer and an outer layer that quickly evaporates excess moisture. The two layers create dead air space, which is the best insulator to keep heat close to the body. Saddle shoulder: The seam for the shoulder sits in front and in back to add comfort.