1. 5 balls have less friction and are relatively light in weight. They have the advantage of fast start and are suitable for short-track speed skating.

2. 6 balls have a strong load-bearing capacity, suitable for skater with strong explosive power and strong strength. recommended for freestyle skating or Pro roller skating.

3. 7 balls are the most conventional bearings, suitable for adults, and recommended for long distance speed skating or marathon races.

4.11 balls are designed for KIDS to roller skate training, and the weight of trainer should not exceed 65kg.To a certain extent, it can make up for the weakness of children's leg strength.