Saf-T Vent Seal is manufactured entirely of AL 29-4C ® superferritic stainless steel. We won’t compromise performance with conventional alloys anywhere in the system. Laser butt seam welds and advanced resistance-welded fittings leave walls smooth inside, to minimize friction and resistance, and prevent collection of combustion by-products. Saf-T Vent Seal is UL 1738/ULC S636 and is Listed to meet all code requirements for condensing and positive pressure special gas vent systems. Saf-T Vent Seal speeds installation on any job. Since no curing is required, Seal allows the appliance to be started as soon as the installation is complete.