As the main manufacturer of soundproof door-oak main door, Guangzhou Casen Door CO.,LTD carries out a strict quality control process. Through quality control management, we examine and refine the manufacturing defects of the product. We employ a QC team which is composed of educated professionals that have years of experience in the QC field to achieve the quality control goal.. We receive important feedback on how our existing customers' experience Casen brand by conducting customer surveys through regular evaluation. The survey aims to give us information on how customers value the performance of our brand. The survey is distributed biannually, and the result is compared with earlier results to identify positive or negative trends of the brand.. At Casen wooden door, we offer expertise combined with personalized, one-on-one technical support. Our responsive engineers are readily accessible for all of our customers, large and small. We also provide a wide array of complimentary technical services for our customers, such as product testing or installation..