The tip allows you to write the thickest line of the nib that makes it easier to draw lines on strong and weak lines.
If you want to attach a strong or weak line as you want, you may need to get used to it.
10 pens with a plastic case for convenient storage.
Uses: Cartoon characters, effect lines.
The line is strong and weak (strong and thick lines, weak for thin lines) means that you can use thick or thin lines depending on the angle and pressure of the nib.
These uses are for reference only, so please use different uses according to the style of your painting or other addictions.

(From Amazon.co.jp)