The operation is child’s play! Simply equip the door handle alarm with a 9V block battery (not included), turn it on, and hang it on a door handle or knob - done! Any movement on the door handle or door will trigger a loud alarm, reliably signaling that someone is trying to gain access to your room, house, or apartment. At the same time, the intruder will be deterred, as they must fear being discovered due to the noise they have caused.