4" DuraVent DirectVent Pro Vertical Wind Guard 46DVA-VWG This vertical wind guard is used only with High Wind Termination Cap when additional wind protection is needed. Fits both 4†x 6 5â„8†and 5†x 8†terminations. 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).