Learn about the UPVC profiles selected for plastic steel doors and windows. UPVC profile is the decisive factor for the quality and grade of plastic steel doors and windows. A good UPVC profile is a rationally designed multi-cavity, with a thick wall and anti-aging and anti-ultraviolet additives in the formula. It looks smooth and white in appearance. The color of high-grade UPVC profiles is white to green, and has good anti-aging performance. The middle and low-grade profiles are yellowish in white and have poor sun protection ability. After a few years of use, they will become more and more yellow until aging, deformation and brittleness. Observe the hardware selected for doors and windows. The hardware of high-end doors and windows is made of metal, and its inherent strength, appearance, and usability directly affect the performance of doors and windows. Many medium and low-grade plastic steels use plastic hardware, and there are great hidden dangers in their quality and life. Observe the assembly quality of doors and windows, mainly to see whether the appearance is smooth and undamaged, whether the welding corners are clean and tidy, whether the hardware is in order, and whether there is steel lining. Check whether the door and window manufacturer has a production license issued by the Construction Committee.