Used for installation of a vertical concentric exhaust/CG gas intake on a Rinnai RU160IN tankless hot water heater. I screwed up by not realizing the sealant I used had petroleum products which will break down the plastic over time. I realized before it had fully cured but, we then had 4 days of intense rain...I plan to get a new metal roof installed within the next couple of years. So, I hope it holds until then. Don't make the same mistake and be sure to use some polyurethane sealant on this item, nothing with asphalt