One: The use of low-cost general-purpose plastics-polyvinyl chloride (PVC) insulated strips for non-structured materials can be used instead of fiberglass reinforced polyamide nylon (PA66) insulation strips. Second: first imported nylon (PA66) insulation strip assembly of the Insulation sample window to participate in the bid, after the winning bid for the actual processing of PVC heat insulation strip, or the import of nylon (PA66) insulation strip and PVC insulation or other materials mixed use, and the import nylon (PA66) insulation strip has the trademark logo face outward, to "prove" the "grade identity" of the insulating strip. This trick is very concealed, only in the case of the profile has not yet been processed to identify, the internal quality of doors and windows is very harmful. Third: 2003 domestic nylon insulation strip to market, in order to reduce costs, domestic nylon insulation used in general mineral materials (commonly known as filler) in all or part of the substitution of glass fiber to fill polyamide nylon processing production. The insulating strip is not comparable to the glass fibre reinforced polyamide nylon (PA66) insulation strip in terms of mechanical strength, heat resistance, anti-aging properties. Fourth: Some enterprises in the study, grasp the PVC insulation strip, domestic nylon insulation bar, after the large performance difference between the fiber reinforced polyamide nylon (PA66) insulation strip, the economic and insurance Compromise is adopted: the window frame aluminum adopts low quality and inexpensive PVC or homemade nylon insulated strip, the sash aluminium profiles adopts high quality imported nylon (PA66) insulation strips.