... ,17C,18A,18B,18C,19A,19C,20A. 3.Usage: Machine Structural. Standard: JIS G3445Grade: STKM11A, STKM12A, STKM12B,STKM12C, STKM13A, ... ,STKM17C, STKM18A, STKM18B,STKM18C, STKM19A, STKM19C,STKM20A.Usage: Machine Structural Purposes.FOB Price/MT:USD700-1,680.00MOQ:10MT Usage ... : Carbon Steel Tubes for Machine Structural Purposes.Surface: Annealed/Pickled/Polished.Ends: Plain ends or ...