In calligraphy practice, what is Yan Kai's requirement for hairiness of writing brush? Ask the great god for advice?

The strokes of face and body are thick, so it is difficult for beginners to write thin lines because of unstable techniques and heavy movements. Face and body are more practical, which requires a brush with strong ink storage capacity, with a peak value of about 4cm and a slightly larger front diameter, which is convenient for writing. You can compare the ink pool brush.