Drains - trying to take to mean them - direction please? I now know what an interceptor cap looks similar to. What...

I now know what an interceptor cap looks similar to. What is the thing called that it screw onto and is chained to (the thing approaching a giant vacuum flask)?
Bought a 5300 btu single room a/c to...
Answers:    Are you trying to install a bathroom drain or a faucet? It sounds like a bathroom but I'll venture a guess as the giant vacuum flask is probably the dampen pump (is it a large black, full of air kinda plastic bubble/bag point?).