Whether at work, rest or play these Heat Holders Thermal long johns will keep you nice and toasty. Heat Holders thermal construction holds more warm air close to the skin, keeping you warmer for longer! They are rated at TOG 0.45. What does 'TOG RATING' mean? TOG is a recognised measure of a textile's thermal ability. Simply put, the higher the TOG rating, the better a product is able to keep you warm. The ribbed construction of these Long Johns shapes to the bodies' natural contours and that along with the soft brushed insides maximises the warmth! The cotton blend provides natural softness and comfort.