1.Easily mounted by adhesive tape to window or door. 2.Magnetic sensor switch detects entry protecting your home or office whether you are in or out. Due to different factory batches, the product words are different, and the product accessories have slight differences in color and appearance, but it does not affect normal use Open the battery cover,Match positive and negative signs and Insert 2 xAAA batteries(not includ) correctly, close the battery cover Fix the main unit which has on-off switch at the side of the door&window. Attach the magnet to door /window frame with the aligning with the referenc line of the main unit. Switch to"ON" position of the main unit so as to be in alert state,it give an 90bp alarm if the magnetic senor has been separated fron the alarm device when someone opens the door/window. Please turn off the switch when you don't need Remove the batteries to prolong the of the product/batteries if it be set for a long time Colour:White Material:ABS Package Contents: 10 x Door magnetic 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.