Thanks, our home stores don't carry them and I can't make it to the plumbers' supply during the day, so at first I made them myself.
But, I was a moron and made them with 4" boots when I needed 3" so I whipped them in the trash furiously. When I bought the 3" boots I was lazy and just slipped the whole flashing right over.
Getting a new roof in the fall... it was hard to care at that point
Oh, you meant as a permanent replacement. I just figured all new flashings with the new roof so I was just trying to stop the leak for now. I saw the Oatey rings online but thought they were meant to slip over and act as a rain collar, not as a permanent repair. Thanks for the tip.