Metal Pall Ring 1.material: SS316, SS304, SS304L, etc 2 size:16mm,25mm, ... protection, etc. Geometric ParametersSizes(mm)Bulk density(kg/m3)Number (per m3)Surface area(m2/m3)Free volume (%)16*16*0 ... steel including 304, 304L, 410,316, 316L. YIQUAN metal pall ring for petrochemical industry