Coolpass is a brand name for a high-performance, functional polyester fiber known for its superior moisture-wicking and quick-drying capabilities.1It is engineered with a special cross-shaped + fiber section that utilizes the capillary effect (siphon theory) to rapidly draw sweat away from the skin and quickly spread it across the fabric surface for accelerated evaporation. Function: Keeps the wearer cool, dry, and comfortable. Mechanism: Cross-section fibers and capillary action (similar principle to Coolmax, but with a different fiber shape). Primary Use: Sportswear, activewear, jerseys, casual wear, and underwear.