Advantages: Combining traditional calligraphy with modern scientific knowledge, using the knowledge of golden section, lever balance and perspective principle, the "trapezoidal grid calligraphy method" was created and won the national patent.

Disadvantages: 1 Easy to use, but the upper limit is not high. Zhao Rufei's price is high, and other calligraphy practice institutions are generally cheaper than him.

Another fact is that children are writing a complete trapezoid, but they can't change it in Tian Zi.