Any effective thermal wear system starts with a performance layer next to the skin. The Heat Holders Microfleece Base Layer Long Sleeve Top is made with a specially developed lightweight microfleece that has an excellent weight to heat ratio, a highly breathable construction and, flat, non-chafing seams and multi-dimensional stretch, making it very versatile.The top has a quarter zip collar, with a protective chin guard that enables venting as well as heat retention. Heat Holders Microfleece Base Layer Long Sleeve Tops are TOG (Thermal Overall Grade) rated to 0.61 so you can be sure you will be warm.(11/14)