... , UL, usage:structure, liquid transfering,sprinkler syetem.frame,fence tube steel tubeincluding ERW and Seamless, round and rectangular ... . SIZE: 16mm-508mm, Wall thickness:1mm---20mm. PURPOSE: fluid tube, fence tube, structural tube, scaffolding tube, water transferring tube ... fire fighting system tube (with groove available), furniture tube, fence tubes and so onCERTIFICATE: ISO9001, UL, FM, CE, ...