国产色视频在线播放,欧洲成人一区二区,欧产日产国产蜜网站,一级大片儿,毛片**免费看,一级黄色日本片,久久69视频

PD type parallel clavis belongs to the connection fittings in power fittings. PD type parallel clavis is used for connecting single boards to single boards and single boards to double boards, and can only change the assembly length, not the connection direction. Parallel hanging plates are often made of medium thick steel plates through stamping and cutting processes. The standardized parallel hanging boards are divided into single board parallel hanging boards, double board parallel hanging boards, and single board converted double board parallel hanging boards.