energy source battery powered Number of batteries 3 LR44 batteries are required. (include) About this project Loud Alarm: The 120 DB security alarm is perfect to signal you when there is an unwelcome entry. It's loud enough to be heard at over 750 feet, so people know they should stop what they're doing. Great for preventing, protecting your kid's room or stopping anyone from sneaking out or in. Wireless Alarm Sensor: No wiring required, each device includes 3 LR44 batteries. These batteries in the siren can last 6 - 12 months on a long charge. When it changes, you'll know. With the intuitive low battery indicator, you can easily find out when the battery needs to be replaced. EASY TO INSTALL: The wireless security siren can be installed anywhere there is an opening. Just use the adhesive provided and stick it wherever you need it! Windows, doors and entrances with alarms are straightforward. The minimum distance the device will work is 15 mm (0.6 in), so make sure the two parts of the siren are as close together as possible when installing. HOME STYLE DESIGN - With a slim construction and sleek design, these alarms can easily be placed anywhere you need them. Perfect for attaching to doors, apartments of all types, cupboards or offices, place them where you see fit. They may be discreet and easy to install, but don't be fooled, these alerts are powerful enough to stop any unwanted behavior. Package includes: 1* Alarm with tape (battery included), 1* User Manual.