The remote siren plugs into an electrical outlet (and has built-in battery backup). So you can place it anywhere you have an outlet. You will want to place it away from sound dampening furniture and such for better sound dispersion.
The LED security light is pretty worthless IMHO. But it does have a green/red LED that will also tell you if a zone is open. And it also acts as a repeater to provide better coverage. So it is a good device overall.