This INTRUDER ALARM with RF REMOTE CONTROL is a great window or door alarm that can be armed using the included RF remote control. Multiple units can be armed or disarmed throughout your home via three separate radio frequencies. You can also choose each frequency individually to operate different units or sets of units throughout your home. Simply install the master unit and the magnetic sensor bar on teh frame of any window or door with the included adhesive tape. If the door or window is opened, it will sound an ear splitting 110 decibel alarm. This is a very cost effective solution for preventing intruders or alerting you of an intrusion. Master unit requires three AA batteries (not included). The remote control requires three LR44 batteries (included).