I assume Yonex has a very high quality control making rackets. However JP designated rackets are selling way higher prices, than other country coded ones, they should not be any better or worse, otherwise the company shooting itself in the head. I generally buying rackets from Hong Kong with SP designation, and I noticed there is some discrepancy on the size of the grips. Last Monday I received a new shipment from HK, a Yonex Voltric Z Force II, 4U/G5 SP and an Astrox 100 ZZ also 4U/G5, and immediately become apparent, that the grips are not identical. I have 2 other Voltric Z Force 4U/G5's about 3 months old from the same supplier, so I checked the grip diameters on all of them. Turns out that these 3 months used racket grips now are 82 mm in diameter, the brand new Voltric Z Force II is 83 mm, and the Astrox 100 ZZ is 81 mm. Where is the quality control of Yonex. It would be difficult to believe that for different models the grips sizings with the same numbers are different , but surely the G5 grips are for the Voltric Z Force are 83 mm diameters from the factory, yet the G5 for the Astrox 100 ZZ is 81 mm. YONEX SHOULD BE MORE CAREFUL ON THIS ISSUE.