Regulite fabric Fibre blend of natural merino wool and synthetic polyester Lightweight Wicks away moisture Quick drying Naturally anti-microbial and odour resistant Cut and sew construction with flat-locked seams Reflective graphic Head out on your run with the comfort and cooling performance-enhancing support of Ronhill's Infinity Merino Blend Long Sleeve Running Top. Merino wool is an outstanding material - it keeps you warm when you are cold and keeps you cool when you are hot. Finer than traditional wool, Merino wool is smoother and more comfortable - the quantity/density of fibers results in superb insulation qualities - trapping more tiny air pockets, locking in body heat in cool conditions. In the heat Merino works as a condition buffer - cooling the body initially by managing the build-up of moisture vapour internally, keeping you drier for longer.