Yep. It's the diverter for the shower head. One of those push button ones that there are no parts for. If I can take it out and screw in this plug to eliminate it, I can buy a tub spout with a valve in it. Otherwise I need to open up the wall to gain access to the whole tub valve for replacement. Ceramic tile and wallpaper are involved and a simple fix could end up doing a whole remodel. :mob::mob: