You can use one of our thread tapes or pipe joint compounds to complete this application. If you are using thread tape, wrap the male threads on the tail piece 2 or 3 times, and then screw the tail piece into the pop-up body. After the drain has been tested and found to be water tight, you can cut the excess thread tape off if desired. If you use pipe joint compound, only apply it to the male threads of the tail piece and wipe off excess after the drain has been tested.