Door piers, also known as door seats and pedestals, are used in East Asian traditional buildings. The bottom of the door is a component that supports the door frame and the door shaft. Most of them are made of stone, but there are also wooden ones. The whole is called the door pillow stone, and the part outside the door is called the door pier. There are mainly box-shaped and drum-shaped (drum-shaped stones). The door pillow stone has a slot in the middle to support the door frame, and the inner part of the door has a sea socket for inserting the door (the lower end of the door shaft), which together with the couplet fixed on the middle sill, serves to fix the door shaft, which is convenient for the door. The role of the switch.