【A Must Have In Winter】Our thermal underwear for boys has styles suitable for all ages from toddlers to teens(Ages 3 to 16). Our kids’ thermal long johns and vests set, almost acting as 'second skin', will keep them comfortable and warm in cooler weather. The fleece-lined design of this long johns set not only maintains the body’s heat but actually helps generate heat by absorbing body moisture.【Stretchier Fabric&Comfortable Fit】The innovative technology makes tight fit of this thermal clothing, while also adding stretch for active youngsters. The perfect fit, thanks to its precise cut, guarantees unrestricted freedom of movement and minimize risk of chafing. The shirt and the legging are fitted but not too skintight. So you can wear it comfortably by itself, yet it won’t bulk up if you wear it under a sweatshirt.【Retain Shape for Machine Wash】This great thermal underwear for boys can go into the wash a lot more often and stand up over time to washing and drying. The fabric of this base layer not only provides just-right stretch but also “gives” yet retains its shape wash after wash. A simple plain crew-neck top with a shallow collar stay hidden under outer layers like heavy jackets, bulky sweaters, quality ski-wear and more.【Sweat-Wicking&Moisture-Wicking】Our thermal base layer for boys allows airflow for breathability. Our moisture-wicking technology is meant to keep you dry and comfortable during the workout. The new technology of this thermal long john set prevents the growth of odor-causing elements to leave you feeling fresh throughout the day.【Versatile Use From Outdoors To Indoors】 Because these pieces of this thermal underwear for boys are so soft, this sweat-soaked underwear are good at transitioning from outdoors to indoors. With a wider range of sizes for ages from 3 to 16, the tops and bottoms of thermal base layer set for kids are ideal for running, jogging, field sports, snow playing and more in cooler weather. Your boys can enjoy so many muddy adventures!