F-grade DMD (6641) polyester film polyester fiber non-woven soft composite material Features and Applications: Polyester film polyester fiber composite material is a composite material made of polyester film coated with F-grade adhesive on both sides, and polyester fiber nonwoven fabric on both sides. The heat resistance rating is F grade, with good dielectric performance and high mechanical strength, suitable for Y series and J02 series motors, as well as slot and turn to turn insulation in electrical appliances.