Material purchase is the next step of quality control. We need to select the correct suppliers and supervise their job. We have been working in this industry for so many years; most of the material suppliers have been cooperated with us for many years. The suppliers have passed the exam of our factory and our customers. And the supplier should provide the QAC for each material supply. Our factory quality inspection department will make the material sampling re-examination. And some time, we will send the material to professional laboratory for a third party check to make sure the supplier doing well all the time.