The Oneill Thermo-X is base layer insulator, which can be worn under your winter wetsuit for added warmth. Alternatively can be worn with boardshorts in cool to warm water temperatures, perfect for UK summers. Oneills 13OZ Powerstretch fabric provides incredible insulation with low bulk and quick-dry properties. This thermal offers great flex and breath ability thanks to the Flatloc Stitching and 4-Way Stretch Fabric. 13OZ Powerstretch with DWR Coating, 4-Way stretch fabric. Flatloc Stitched. Water Repellency, Odor Resistance, 4-Way Stretch Fabric, Boardshort Connector, Rash Protection , Strategic Seamless Paddle Zones, Super Low Crew Neck, ,