The Oneill Thermo is base layer insulator, which can be worn under your winter wetsuit for added warmth. Alternatively can be worn under boardshorts in cool to warm water temperatures, perfect for UK summers. Oneills 8OZ Polypropelene provides excellent insulation in a minimal bulk fabric. This thermal offers great flex and breath ability thanks to the Flatloc Stitching and 4-Way Stretch Fabric. 8OZ Polypropelene, > 4-Way stretch fabric. Flatloc Stitched. Water Repellency, Odor Resistance, 4-Way Stretch Fabric, Rash Protection , ,