You need to cut open the system, which means loss of refrigerant gas (should be captured really, rather than just vented), then solder this in, making sure it's leak free. That means afterwards the system needs to be evacuated with a vacuum pump and recharged with gas. You'll need slightly more gas than before.
It's not a capillary tube, so no issues with pressure or throughput. It seems a rather small area for a heat exchanger though, so I doubt it will help much. Also, you can gain virtually the same benefit without having to cut open, vent, evacuate and regas the system by running the water pipe parallel and tied to the existing return pipe (before the air condenser), and over a greater length than this thing.