Century-Line brand wall sleeves like this CS-6 model are made of strong high impact HDPE. This plastic sleeve is a fraction of the weight of steel sleeves and it won't rust or corrode! Must install before pouring the wall or barrier. Compatible with Link-Seal modular seals. Model: CS-6, Material: HDPE, ID (in.): 6.14, ID (mm.): 156, lbs: 3.6, Kg: 1.63