With the GE 51107 Wireless Door and Window Alarm System a 120dB alarm will sound when a window or door is opened. The system is activated or deactived using a 4 digit keypad code. A 45 second delay on the door alarm gives you time to leave without triggering the alarm system as well as a 30 second delay for entering the home. Each window sensor has a concealed power switch and an armed/disarmed indicator light. The system is completely wireless so installation is a breeze. Provide security and peace of mind with a simple to use and install security system. Add security to apartments, dorms, and other locations where you can not do a hardwired or complicated install. The Door Alarm requires 3 AAA Batteries (sold separately) while the Window Alarms use 4 LR44 Batteries (included).