... .8-1.2mm material: q195-q235 finishi: black annealed Steel window hollow sectionsize: 28*28, 38*38thickness: 0.8-1.2mmmaterial ... 304 High pressure steel prof...tolernace: normal standard toleranceShape: round,square,rectangularsurface: pickled, acid, polished, black,ectcertificate: ISO, BV, API, CSC ... is supplied with shipment, Third Part Inspection is acceptable. Steel window hollow section