Im Laura with Renaissance Roofing and these are pipe flashings or plumbing jacks. They go on the roof for where pipes penetrate your roof. Pipes have to come up through your roof to service the house below. Every drain in your house has a pipe that penetrates your roof. to protect your home you want to put these on there to prevent water from coming in. This is what a lot of roofing contractors use, its a low end jack that lasts about 20 years. This is a high end lifetime jack that we prefer to install at Renaissance Roofing. At Renaissance Roofing we believe in helping people get quality roofs for their investment. We aim to bring you a great roof done right.