... ,17A,17C,18A,18B,18C,19A,19C,20A. 3.Usage: Machine Structural. Standard: JIS G3445Grade: STKM11A, STKM12A, STKM12B,STKM12C, STKM13A, STKM13B ... .FOB Price/MT:USD700-1,680.00MOQ:10MT Usage: Carbon Steel Tubes for Machine Structural Purposes.Surface: Annealed/Pickled/Polished.Ends: Plain ...