A compact and fast building that does one thing good: it puts fluid from one vessel to another. Either small(barrel) to big(pipe), or vice versa. WARRANTY VOID if attempting to perform injections on human (or not) characters.

Building size: 2x1, even if it looks square. Also works as a pipe and lets fluids through!
The input and output versions can be converted between each other freely, and exist because of technical limitation.