5" DuraVent DirectVent Pro Double-Wall Black 90-Degree Swivel Elbow 58DVA-E90B This elbow is used to offset obstructions as needed. Fully unitized twist-lock construction. Elbows swivel allowing the lock to remain fully engaged while aligning to the desired direction. The angle will remain fixed at 90 °. Provides combustion air and exhaust venting for gas appliances Clearance to combustibles mandated by appliance listing The components twist-lock together for a quick secure fastener-free installation 0.020" aluminum inner 0.018" steel outer Offsets venting obstructions .020” aluminum inner wall .018” galvanized steel outer wall Painted outer walls made of laser welded .018” galvalume steel. Caps also available in stainless steel and copper. Outer pipe brings combustion air to the appliance. Inner pipe exhausts flue gases to the outside. Gaskets or sealants not required (unless specified by the appliance manufacturer).