http://why-is-polyester-staple-fiber-the-popular-new-age-fiber.bravesites.com - The three dimensional crimp, combined with the hollow, gives superior resilience and insulates the final product. Hollow conjugated polyester fibers (HCS) are widely used in a number of applications.The three dimensional crimp, combined with the hollow, gives superior resilience and insulates the final product. Hollow conjugated polyester fibers (HCS) are widely used in a number of applications.The three dimensional crimp, combined with the hollow, gives superior resilience and insulates the final product. Hollow conjugated polyester fibers (HCS) are widely used in a number of applications.