Utilizing SBR MESH, the 2XU Active Tri Singlet delivers maximum airflow and moisture control through it"s high filament polyester yarns. Complete with pockets and UV protection for long days in the sun. SBR MESH fabric is engineered for swim, bike, and run. This refined mesh structure of this fabric facilitates greater airflow and boasts softness for comfort. High filament polyester plus elastomeric yarns offer flexibility.