Thermal mid layers form an essential part of your layering system during cold weather. They can be worn next to the skin or over a thermal base layer, and should be close fitting without being restrictive. For high activity sports in cold weather, such as skiing, then it is better to wear a thermal mid layer top without the mid layer leggings to prevent over heating. If there are long sedentary periods such as when fishing or sightseeing at the poles, then both a thermal mid layer top and bottom are recommended.
Meraklon thermal mid layers are manufactured form a polypropylene fabric with a brushed inner fleece face. The soft cotton feel to the thermal mid-layers and their hypoallergenic properties make them ideal for children, the sedentary eldery, and people with sensitive skin.
Factor 2 thermal mid layers are manufactured from virgin polyester and are heavily brushed on the inside face to produce a denser fleece than the Meraklon. A hydrophillic treatment applied to the fabric actively transports moisture and perspiration away from the body, keeping you dry and warm. With a more athletic cut and greater technical features, Factor 2 thermal mid layers are more suited to active outdoors people.