The function of the hydraulic buffer door closer is to protect the door frame and door body to close smoothly. When the door is opened, it can be released after compression to close the door automatically. We can see this kind of door closer in major business circles and public buildings. The rdc-04 concealed fire door closer of Lelang hardware can be selected as the hydraulic buffer door closer, which can flexibly locate, release more space, and load-bearing door weight can reach 35-60kg.