Optimum size of calligraphy paper ruler

Weighing ruler is stationery for study, and its main function is to press paper to prevent it from wrinkling or being blown by the wind, which will hinder writing.

Weighbridges are mostly strip-shaped, and there is no length regulation, so the application is better. Of course, it's too short for paper to slide and it grows heavy, so it's generally more than 20 cm.

For example, there are two kinds of dead city scales:

At the end of the Ming Dynasty, Shi Sou copper inlaid silver wire weighed 24.7 cm; In Qing Dynasty, the ivory bamboo town ruler was 25.3 cm long.