The board type is an internationally popular roofing board, which is characterized in that the button-type undercut self-locking coupling parts are all hidden and installed, and no screw is exposed on the entire roof. It is quick and easy to install, has good cross-sectional characteristics, and has a lifespan more than 2 times that of ordinary profiled steel plates. It has no leakage and is suitable for all roofs. It is the main replacement product in recent years. Equipped with arching forming machine, it can produce arched roof system with skeleton.