I'm wondering if someone could help me identify what this fitting is. The tub drain pipe
and overflow pipe join together via a T fitting and then into this fitting. Then the pipe exits
the fitting and presumably exits to the basement. The house is old so there is no P trap.
I currently have a back up into the tub and I'm wondering if this is a trap that can be cleaned
out. I ran some hot water down the tub and felt warm pipes up until this fitting, but not after.
Any information would be helpful. Thanks!