The Great blend of fit-warmth-wicking, the Mammut Zip All-Year Longsleeve Shirt for Boys features a performance fit with blended polyester microfiber / warm Merino wool and wicking body mapping to maintaining the optimum body temperature. The ideal performance baselayer for every winter adventure, 3 different moisture wicking fabrics that are strategically placed around the arm pits, sides and elbow warm when necessityed and vent where necessityed. This shirt is antimicrobial treated to avoid the fallout of unpleasant odor after multiple of long use.