Badminton ball number mark means that there is a speed mark on the badminton barrel (pictured). At present, there are mainly signs 76, 77, 78, 79, 1, 2, 3, 4, 7, 8 and 9. The smaller the tag value, the slower the ball speed, and the larger the tag value, the faster the ball speed. 7, 8 and 9 are training balls, which are generally suitable for beginners. Other models are common.