Versatile Usage: tear off the double sided tape to fix the host on the door or window side, and paste another strip of door magnet in a straight line along the host prompt line on the door frame; Check the setting by turning the host switch to the "ON" position; Open the door and see if the door and window security alarms sound Package Contents: you receive 24 pieces of window alarms for home security, sufficient quantity to meet your usage needs, replacement needs and sharing needs, small size, suitable for many kinds of doors and Material: ABS colour: white Package Contents: 24 x Door And Window Alarm 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.