Helly Hansen Mens LIFA Crew Thermal Black is a performance base layer, delivering lightweight insulation and comfort for everyday use and high performance activities. HH LIFA® is constructed with 100% Lifa® fibers that are quick-dry, extremely breathable, and super lightweight. Continually perfected over the last 40 years, Lifa® Stay Warm technology is the unique ingredient of all Helly Hansen base layers.