https://swaay.com/u/gordonperkins33101/about/">https://swaay.com/u/gordonperkins33101/about/. A quality roof will have them installed all over the side of the roofline, where vertical wall surfaces fulfill the roof https://blanchelouv284012.bloggazza.com/38312462/the-5-minute-rule-for-stay-dry-roofing