So you may be wondering why I chose to use an RF module instead of just using a wire to connect the "transmitter" and "receiver". My thinking is that, if you had a break-in, the intruder would see this wire and follow it to your receiver and tamper with your evidence of their break-in. You could hide the wire here I suppose, but there's still going to be spots where it may be visible.
So with RF you can hide the receiver lots of places (generally need a power outlet now, if you want to leave it for extended periods of time) and an intruder would really need to search out your residence to find it.
If the intruder has sophisticated equipment that makes finding RF modules easy, well you need other ways to protect and defend against these intrusions. This module won't help much besides making the attacker work more.