Terramar Body-Sensors Lightweight Helix Half Zip Shirt - Men's fabric Constructed of soft 100% micro polyester with two sided knit construction. Designed to create air pockets for improved insulation and moisture transport. Lightweight temperature control layer prevents moisture build-up during intense workouts. ec2 Qwik-Dri Thermoregulation Comfort Technology is an electrostatic process that allows for moisture movement without the garment touching the skin. Versatile 1/2 zip mock with zipper garage lets you zip up for maximum heat retention and unzip for ventilation.