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 the doors 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 coming and going when you're at home. 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.