Men's Thermal Underwear Top Heat Holders thermal construction holds more warm air close to the skin, keeping you warmer for longer. Heat Holders thermal underwear is the perfect underwear set for layering, as of its easy fitting design for under your clothes. This helps make 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. This makes it hardly noticeable under your clothing. The base layer is made of a cotton-rich blend, which gives you natural softness, and warmth, for all-day wear. This shirt has a longer length body so that the vest is able to be tucked in to 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 long johns also available in separate listings, or a short sleeve version of this shirt. We also offer women's sizes/colours. Extra Product Details - Thermal Long Sleeve Shirt - 4 Sizes - 2 Colours - 0.45 TOG - Super soft & comfortable - Ribbed construction - Cotton Rich - Seamless body - Longer length body - Long johns also available