The drain "collar" in my bath tub is almost completely corroded and there are black spots under what may be plumber's putty. I thought it would be a simple "remove the drain and replace it with a new one" type of job. Great, I can do that myself. But this morning, after Googling, the drain part I see may need accessories that should be used to connect to the drain pipe. My home is on a cement pad with skirting around it. If things need to be connected then a plumber will need to crawl underneath; no way would I consider this something I could do and do it right.