Rectangular heavy/double build Dacron glass is a served filament that is applied over the magnet wire conductor. Dacron glass is a combination of glass and polyester fibers. The fibers may be served over bare conductor or Therm-Aimid insulated conductors. Daglas-film constructions provide improved electrical properties. Machine windable. - Rectangular heavy/double build Therm-Aimid is a dual film insulation system composed of THEIC modified polyester with a polyamideimide (AI) overcoat. Therm-Aimid, designed for continuous operation at 200 °C, provides superior abrasion resistance, solvent resistance and overload protection.