The threshold is the old name of the lower door frame, also called the lower threshold, and it is the largest cross material of the door frame. If the outer door is provided with a lower door frame, it can play a wind-proof role and solve the wear problem, and then the surface layer can be wrapped with metal sheets or added with battens for easy replacement.

Generally speaking, the height of the threshold is not too particular, generally about one meter, but there are many other stresses on installing the threshold stone. The color of the threshold matches the five elements of the householder, and the five elements of China have their own representative colors. It is more convenient to lower the threshold if you have children at home.