Mens Thermal Underwear Top Heat Holders Thermal construction holds more warm air close to the skin keeping you warmer for longer. This set of thermal underwear is the perfect set for layering as of its easily fitting design for under your clothes for a smooth slim fitting thermal base layer for the colder days where one layer isn\'t enough! This thermal underwear set has a TOG rating of 0.45 adding that crucial extra layer of warmth. The higher the TOG the better the garment will keep you warm. The ribbed construction of this thermal underwear has been designed so that it effortlessly shapes to the bodies natural contours - helping to provide the best fit possible making it hardly noticeable under your clothing. The base layer is made of a cotton rich blend which gives you the most natural softness and warmth for all day wear.This shirt has a longer length body so that the vest is able to tuck in and stop cold drafts. It also has a seamless body which reduces the risk of irritation for all day comfort. The thermal underwear set comes in 2 colours (Grey and White) and there are matching bottoms also available in separate listings. We also offer womens sizes/colours.