Boys Ski Thermals from top brands, using the best merino wools - shop Icebreaker, Odlo, Reima, Helly Hansen. Merino wool is naturally anti-bacterial meaning no nasty smells, it wicks moisture away fast and is warm and comfortable next to the skin. Don't like merino wool? No problem, polyester thermals are great for wicking moisture away too while working hard on the slopes and are good at keeping you warm and regulating body temperatures. Just don't use cotton thermals - not designed for active sports and stay wet and soggy ensuring you get chilled on cold ski lifts!