Shen Shi and Kong Xuan belong to the ternary school. If you want to buy a compass, you can buy a ternary disk. The characteristic of ternary plate is that there is only one floor in the twenty-four mountains, and the yin and yang of the mountains are connected by three Yin San Yang, so it is easy to distinguish them.
The 4-inch plate is too small, and it is generally only used for sterilization or portability. Because it is too small, it is easy to make mistakes when using, especially for beginners. If it really needs to be used in a house, it should be at least six inches. The most important thing is that Tianchi is bigger.