This is a 16" plastic wall sleeve made from durable and impact resistant HDPE material. Also known as polypropylene, this plastic is rust and corrosion resistant. It also is much lighter than traditional metal sleeves and makes for easier install. These sleeves are made by Century-Line, the manufacturer of Link-Seal pipe seals.Model: CS-16, Material: HDPE, ID (in.): 16.18, ID (mm.): 411, lbs: 12, Kg: 5.44