Usage Tips:COMPREHENSIVE PROTECTION - These door and window alarms sensors provide a comprehensive protection plan for your home security, office, or any living space. With the ability to use one for a door and one for a window, or both for windows, this cost-effective solution will keep you and your family safe. INSTANT ALERT - Help secure and windows of your home, office, or apartment with the 120 dB door/window alarm or chime. Easy to use and deafening alarm will alert you and your neighbors of an intruder, or deter intruder. An attention-grabbing alarm is audible hundreds of feet away. Compact magnetically triggered alarm sounds when a window or door is opened. CUSTOMIZABLE SETTINGS - Easy to change from Off/Chime/Alarm setting alerts you when people/children are and going when you're . No worry about the alarm being deafening, quickly press the button to adjust the volume as you need (from 85 dB to 120 dB). EASY INSTALLATION - The simple, wire-free design of the alarms is perfect for homes, apartments, dorm rooms, and offices Security. each alarm is powered by 4 x LR44 button batteries (included). Colour:White Material:plastic Package Contents: 4 * Door Window Alarms Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.