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D4HB / D4BA ????????? ??
????? ?? ?? ?????? ?? ????? ??? ? ???? 20 ???? ??? ???? ???? ????? ??????? ????????? ????? ?? ???. ????? ? ???? ?? ???? ?????. ????? ?? ISO16949 ?? ????? ???? ??? ???? ??? ? ， “High Sealing cylinder head” 、 “the long berguna life of silinder head” and the other 5 Utility model patents.
