The North Face has developed the new HyActive system so you can find the ultimate layering piece, no matter where you are or how intense the outdoor experience. Rapid wicking and quick drying times help keep your skin comfortable for longer, and these baselayers are also highly odour resistant and hypoallergenic. HyActive Light uses an open piquet structure to enhance moisture transport and evaporation, making it perfect for high energy activities in warmer weather.HyActive Warm has a two-layer construction that traps warm air for thermal protection, great when skiing or mountaineering in colder conditions.