The Quiksilver 4/3 Marathon Sessions Back Zip Wetsuit is engineered from StretchFlight neoprene, renowned for its superior thermal warmth and flexibility. Certified eco-friendly by Bluesign®, the lightweight design provides an unrestricted fit so you can stay agile without feeling weighed down. To protect against cold water chill, a state-of-the-art infrared thermal lining captures your body heat to transform it into warm energy - for unmatched comfort in every session. Other features like the exterior fluid seam weld and smooth skin paneling all enhance the overall warmth of the Marathon Sessions.