How to treat the production date of badminton rackets?

Look at the steel number on the cone cover. From left to right, 1 and 2 digits are days, the 3rd and 4th digits are months, and the 5th digit is years.

Playing badminton is an over-the-shoulder exercise, that is, the wrist and elbow move beyond the shoulders. It is easy to cause shoulder fatigue when the shoulder is over for a long time. The impact between humerus and acromion may cause subacromial bursitis and medial humeral condylitis.

People have different views on the origin of badminton. 14-15th century, the original badminton racket appeared in Japan for the first time. It is a racket made of wood, and at the same time, feathers are inserted into the cherry pit to make badminton. This is the first formation in badminton history. However, due to its low robustness and slow flight speed, this design soon gradually disappeared from people's field of vision.

/kloc-Around the 8th century, a game similar to the original Japanese badminton began to appear in India. Their balls are made of cardboard with a diameter of 6 cm and a hole in the middle. Against the background of feathers, they became badminton. In India, this sport is called Pune.