5" DuraVent DirectVent Pro Black 3" - 14 1/2" Pipe Extension 58DVA-16AB This pipe extension is used to add length to a straight length of DirectVent Pro. Adds 3" to 7" of length. Direct vent lengths feature a fully unitized twist-lock construction. Use of sealant is optional unless specified by the appliance manufacturer. Does not fit DirectVent GS pipe. 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).