Can be easily mounted by adhesive tape to window or door Magnetic sensor switch detects entry Operated by 3 pcs 1.5VLR44 button cell (included) Super loud 90 dB alarm Color: White door entry alarm,window entry alarm,alarm system Size: About 6.2*3*2cm,5.4*1.3*1.1cm Weight: About 40g Battery: 3*1.5V LR44(include). Instructions: 1.Use the double-side adhesive tape to fix the main unit at the side of the door/window.Attach the bar magnet to door frame/window frame with the refernce line of main unit. 2.Test the setup by swithing the system's swithing to "ON" positon of main unit and see whether the alarm can be triggered by opening the door/window. A high quality security systems alarm is necessary for every house. Now as we are becoming increasingly busy and being surrounded by various electric equipment, security systems alarms can warn you in time to get away from danger., installing a security systems products would not cost you much time and money, but the system alarm can surely help you live a much safer life. Now the system alarms in our shop are under promotion, come on and choose a new set for your house!