... , EN, BS, JIS, UL, galvanized, painted rectangular, square certificate:CE, ISO9001 square steel tube, rectangular or square, according to standards ASTM A53, ASTM A106 ... : 16mm-300mm, Wall thickness:0.8mm---20mm. PURPOSE: fence tube, structural tube, scaffolding tube, furniture tube and so onCERTIFICATE: ISO9001, UL, FM, CE square steel tube