... HL,200# polishing, 400 # polish precision tube 321 Stainless steel is a production which not easy rust ... and so onProduction technologySeamless steel pipeWelded steel pipeSurface treatmentPolishing or notThe stainless steel barstandardASTM,GBmaterial201,202,301, ... 304,316,316L,316LN,317,317L,309,309S,310,310S,430,409specificationRoundSquarerectangle precision ...