I am just curious: In Singapore, we can generally find two types of Yonex rackets. Both types are labelled "SP" after the model names. Example: Ti10 SP, Muscle Power 100 SP, Carbonex 20 SP. But the serial numbers engraved on the cone of the rackets are either "SP" or "HK". What about Yonex rackets in China? Do they have "SP" on the shafts after the model names? ie. Ti10 SP or just Ti10? And what are the letters on the serial numbers engraved on the cone of the rackets?