Loose polyester fibers. Polyester fibers are measured by the "denier". Most fibers that you would purchase in a retail store is a 6 denier fiber. It is soft to the touch. Most mfg. companies use a larger fiber. A larger fiber does not fill as soft, but it has much more "PUSH BACK" power. like the copper wire the larger the fiber the stronger to product. We offer 6 denier fibers and a 15 denier fiber.