Teflon Coated Rubber Expander Manufacturer, Wholesaler in Worldwide!. Teflon Coated Rubber Expanders make an excellent way to avoid sticking materials on the surface. These rollers are also used to prevent interweaving of material in slitting operations. This sleeve once slipped over the roller and heated with a hot air gun, allowing the sleeve to shrink to a tight fit on the roller and achieve the desired result.