This is an 18" extension pipe for the Gen-turi generator exhaust system. It is recommended that the exhaust pipe extend a minimum of 6" above the roof line. While the Gen-turi system comes complete with 10' of pipe you may need a little extra if you have a taller RV, and this extension will allow you to reach the recommended height. It comes with a coupler as well allowing you to connect the pipes together easily. The extension is easy to install and allows the Gen-turi to vent nasty exhaust fumes away from the ground and above the RV's roof line.