Balls are rated by their grade. A Grade 3 ball means that the ball is 3/1000000 tolerance of sphericity, and so is extremely round. In fact, the races of any bearing can’t come close to this level of precision in their trueness, but every component being closer to perfect helps decrease friction. Another feature of Grade 3 is surface finish, which in this case is free of scratches or scuffs, and to a < 0.003 micro fine finish. The lower the grade number, the better is the ball. Fenghe Intelligent Technology Bearings only uses very high grade balls, whether steel or ceramic. Only 10 years ago, Grade 25 would be considered a very high grade ball, used in the best hubs and bottom brackets made. Fenghe Intelligent Technology Bearings starts with Grade 10 balls and then Grade 5 or Grade 3 at the top.

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