Plastic-steel profiles refer to PVC profiles used to make doors and windows, which appeared in Germany as early as the late 1950s. Because the strength of doors and windows made of PVC profiles is not enough, steel is usually added to the cavity to enhance the firmness of the doors and windows. Therefore, plastic doors and windows made of steel added inside the profiles are usually called plastic-steel doors and windows. With the wide use of plastic-steel doors and windows, the PVC profiles used to make plastic-steel doors and windows are customarily called plastic-steel profiles.