The millstone is a white tiger, which is generally used for porch feng shui. Used by the Castle Peak Evil Spirit or the Duan Long Yin Evil Spirit. However, it must be placed after surveying the actual terrain and the situation of Jiugong, otherwise it will be harmful to people's health.
There's a saying that there are no bones left. A millstone is something with a heavy shade. It is best to put it in the northeast or northwest of your home.